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Problem42 符号化三角数

問題

三角数のn項は t(n) = n*(n+1)/2で与えられる. 最初の10項は
1, 3, 6, 10, 15, 21, 28, 36, 45, 55
である.

単語中のアルファベットを数値に変換した後に和をとる.
この和を「単語の値」と呼ぶことにする.
例えば SKY は 19 + 11 + 25 = 55 = t(10)である.
単語の値が三角数であるとき, その単語を三角語と呼ぶ.

テキストファイルに約2000語の英単語が記されている.
三角語はいくつあるか?


ソース

using System;
using System.Collections.Generic;

class Program
{
    //Zが20文字続いたら、26*20が単語の値であり、これを三角数の最大値とする
    const int MaxSankakuVal = 26 * 20;

    static void Main()
    {
        string[] TangoArr = {
"A","ABILITY","ABLE","ABOUT","ABOVE","ABSENCE","ABSOLUTELY","ACADEMIC","ACCEPT","ACCESS",
"ACCIDENT","ACCOMPANY","ACCORDING","ACCOUNT","ACHIEVE","ACHIEVEMENT","ACID","ACQUIRE","ACROSS",
"ACT","ACTION","ACTIVE","ACTIVITY","ACTUAL","ACTUALLY","ADD","ADDITION","ADDITIONAL","ADDRESS",
"ADMINISTRATION","ADMIT","ADOPT","ADULT","ADVANCE","ADVANTAGE","ADVICE","ADVISE","AFFAIR","AFFECT",
"AFFORD","AFRAID","AFTER","AFTERNOON","AFTERWARDS","AGAIN","AGAINST","AGE","AGENCY","AGENT","AGO",
"AGREE","AGREEMENT","AHEAD","AID","AIM","AIR","AIRCRAFT","ALL","ALLOW","ALMOST","ALONE","ALONG",
"ALREADY","ALRIGHT","ALSO","ALTERNATIVE","ALTHOUGH","ALWAYS","AMONG","AMONGST","AMOUNT","AN",
"ANALYSIS","ANCIENT","AND","ANIMAL","ANNOUNCE","ANNUAL","ANOTHER","ANSWER","ANY","ANYBODY","ANYONE",
"ANYTHING","ANYWAY","APART","APPARENT","APPARENTLY","APPEAL","APPEAR","APPEARANCE","APPLICATION",
"APPLY","APPOINT","APPOINTMENT","APPROACH","APPROPRIATE","APPROVE","AREA","ARGUE","ARGUMENT",
"ARISE","ARM","ARMY","AROUND","ARRANGE","ARRANGEMENT","ARRIVE","ART","ARTICLE","ARTIST","AS",
"ASK","ASPECT","ASSEMBLY","ASSESS","ASSESSMENT","ASSET","ASSOCIATE","ASSOCIATION","ASSUME",
"ASSUMPTION","AT","ATMOSPHERE","ATTACH","ATTACK","ATTEMPT","ATTEND","ATTENTION","ATTITUDE",
"ATTRACT","ATTRACTIVE","AUDIENCE","AUTHOR","AUTHORITY","AVAILABLE","AVERAGE","AVOID","AWARD",
"AWARE","AWAY","AYE","BABY","BACK","BACKGROUND","BAD","BAG","BALANCE","BALL","BAND","BANK",
"BAR","BASE","BASIC","BASIS","BATTLE","BE","BEAR","BEAT","BEAUTIFUL","BECAUSE","BECOME","BED",
"BEDROOM","BEFORE","BEGIN","BEGINNING","BEHAVIOUR","BEHIND","BELIEF","BELIEVE","BELONG","BELOW",
"BENEATH","BENEFIT","BESIDE","BEST","BETTER","BETWEEN","BEYOND","BIG","BILL","BIND","BIRD","BIRTH",
"BIT","BLACK","BLOCK","BLOOD","BLOODY","BLOW","BLUE","BOARD","BOAT","BODY","BONE","BOOK","BORDER",
"BOTH","BOTTLE","BOTTOM","BOX","BOY","BRAIN","BRANCH","BREAK","BREATH","BRIDGE","BRIEF","BRIGHT",
"BRING","BROAD","BROTHER","BUDGET","BUILD","BUILDING","BURN","BUS","BUSINESS","BUSY","BUT","BUY",
"BY","CABINET","CALL","CAMPAIGN","CAN","CANDIDATE","CAPABLE","CAPACITY","CAPITAL","CAR","CARD",
"CARE","CAREER","CAREFUL","CAREFULLY","CARRY","CASE","CASH","CAT","CATCH","CATEGORY","CAUSE",
"CELL","CENTRAL","CENTRE","CENTURY","CERTAIN","CERTAINLY","CHAIN","CHAIR","CHAIRMAN","CHALLENGE",
"CHANCE","CHANGE","CHANNEL","CHAPTER","CHARACTER","CHARACTERISTIC","CHARGE","CHEAP","CHECK","CHEMICAL",
"CHIEF","CHILD","CHOICE","CHOOSE","CHURCH","CIRCLE","CIRCUMSTANCE","CITIZEN","CITY","CIVIL","CLAIM",
"CLASS","CLEAN","CLEAR","CLEARLY","CLIENT","CLIMB","CLOSE","CLOSELY","CLOTHES","CLUB","COAL","CODE",
"COFFEE","COLD","COLLEAGUE","COLLECT","COLLECTION","COLLEGE","COLOUR","COMBINATION","COMBINE","COME",
"COMMENT","COMMERCIAL","COMMISSION","COMMIT","COMMITMENT","COMMITTEE","COMMON","COMMUNICATION",
"COMMUNITY","COMPANY","COMPARE","COMPARISON","COMPETITION","COMPLETE","COMPLETELY","COMPLEX",
"COMPONENT","COMPUTER","CONCENTRATE","CONCENTRATION","CONCEPT","CONCERN","CONCERNED","CONCLUDE",
"CONCLUSION","CONDITION","CONDUCT","CONFERENCE","CONFIDENCE","CONFIRM","CONFLICT","CONGRESS","CONNECT",
"CONNECTION","CONSEQUENCE","CONSERVATIVE","CONSIDER","CONSIDERABLE","CONSIDERATION","CONSIST","CONSTANT",
"CONSTRUCTION","CONSUMER","CONTACT","CONTAIN","CONTENT","CONTEXT","CONTINUE","CONTRACT","CONTRAST",
"CONTRIBUTE","CONTRIBUTION","CONTROL","CONVENTION","CONVERSATION","COPY","CORNER","CORPORATE","CORRECT",
"COS","COST","COULD","COUNCIL","COUNT","COUNTRY","COUNTY","COUPLE","COURSE","COURT",
"COVER","CREATE","CREATION","CREDIT","CRIME","CRIMINAL","CRISIS","CRITERION","CRITICAL","CRITICISM",
"CROSS","CROWD","CRY","CULTURAL","CULTURE","CUP","CURRENT","CURRENTLY","CURRICULUM","CUSTOMER","CUT",
"DAMAGE","DANGER","DANGEROUS","DARK","DATA","DATE","DAUGHTER","DAY","DEAD","DEAL","DEATH",
"DEBATE","DEBT","DECADE","DECIDE","DECISION","DECLARE","DEEP","DEFENCE","DEFENDANT",
"DEFINE","DEFINITION","DEGREE","DELIVER","DEMAND","DEMOCRATIC","DEMONSTRATE",
"DENY","DEPARTMENT","DEPEND","DEPUTY","DERIVE","DESCRIBE","DESCRIPTION","DESIGN","DESIRE","DESK",
"DESPITE","DESTROY","DETAIL","DETAILED","DETERMINE","DEVELOP","DEVELOPMENT","DEVICE","DIE",
"DIFFERENCE","DIFFERENT","DIFFICULT","DIFFICULTY","DINNER","DIRECT","DIRECTION","DIRECTLY",
"DIRECTOR","DISAPPEAR","DISCIPLINE","DISCOVER","DISCUSS","DISCUSSION","DISEASE","DISPLAY",
"DISTANCE","DISTINCTION","DISTRIBUTION","DISTRICT","DIVIDE","DIVISION","DO","DOCTOR","DOCUMENT",
"DOG","DOMESTIC","DOOR","DOUBLE","DOUBT","DOWN","DRAW","DRAWING","DREAM","DRESS","DRINK","DRIVE",
"DRIVER","DROP","DRUG","DRY","DUE","DURING","DUTY","EACH","EAR","EARLY","EARN","EARTH","EASILY",
"EAST","EASY","EAT","ECONOMIC","ECONOMY","EDGE","EDITOR","EDUCATION","EDUCATIONAL","EFFECT",
"EFFECTIVE","EFFECTIVELY","EFFORT","EGG","EITHER","ELDERLY","ELECTION","ELEMENT","ELSE","ELSEWHERE",
"EMERGE","EMPHASIS","EMPLOY","EMPLOYEE","EMPLOYER","EMPLOYMENT","EMPTY","ENABLE","ENCOURAGE",
"END","ENEMY","ENERGY","ENGINE","ENGINEERING","ENJOY","ENOUGH","ENSURE","ENTER","ENTERPRISE",
"ENTIRE","ENTIRELY","ENTITLE","ENTRY","ENVIRONMENT","ENVIRONMENTAL","EQUAL","EQUALLY","EQUIPMENT",
"ERROR","ESCAPE","ESPECIALLY","ESSENTIAL","ESTABLISH","ESTABLISHMENT","ESTATE","ESTIMATE","EVEN",
"EVENING","EVENT","EVENTUALLY","EVER","EVERY","EVERYBODY","EVERYONE","EVERYTHING","EVIDENCE","EXACTLY",
"EXAMINATION","EXAMINE","EXAMPLE","EXCELLENT","EXCEPT","EXCHANGE","EXECUTIVE","EXERCISE","EXHIBITION",
"EXIST","EXISTENCE","EXISTING","EXPECT","EXPECTATION","EXPENDITURE","EXPENSE","EXPENSIVE","EXPERIENCE",
"EXPERIMENT","EXPERT","EXPLAIN","EXPLANATION","EXPLORE","EXPRESS","EXPRESSION","EXTEND","EXTENT",
"EXTERNAL","EXTRA","EXTREMELY","EYE","FACE","FACILITY","FACT","FACTOR","FACTORY","FAIL","FAILURE",
"FAIR","FAIRLY","FAITH","FALL","FAMILIAR","FAMILY","FAMOUS","FAR","FARM","FARMER","FASHION","FAST",
"FATHER","FAVOUR","FEAR","FEATURE","FEE","FEEL","FEELING","FEMALE","FEW","FIELD","FIGHT","FIGURE",
"FILE","FILL","FILM","FINAL","FINALLY","FINANCE","FINANCIAL","FIND","FINDING","FINE","FINGER",
"FINISH","FIRE","FIRM","FIRST","FISH","FIT","FIX","FLAT","FLIGHT","FLOOR","FLOW","FLOWER","FLY",
"FOCUS","FOLLOW","FOLLOWING","FOOD","FOOT","FOOTBALL","FOR","FORCE","FOREIGN","FOREST","FORGET",
"FORM","FORMAL","FORMER","FORWARD","FOUNDATION","FREE","FREEDOM","FREQUENTLY","FRESH","FRIEND","FROM",
"FRONT","FRUIT","FUEL","FULL","FULLY","FUNCTION","FUND","FUNNY","FURTHER","FUTURE","GAIN","GAME",
"GARDEN","GAS","GATE","GATHER","GENERAL","GENERALLY","GENERATE","GENERATION","GENTLEMAN","GET","GIRL",
"GIVE","GLASS","GO","GOAL","GOD","GOLD","GOOD","GOVERNMENT","GRANT","GREAT","GREEN","GREY","GROUND",
"GROUP","GROW","GROWING","GROWTH","GUEST","GUIDE","GUN","HAIR","HALF","HALL","HAND","HANDLE","HANG",
"HAPPEN","HAPPY","HARD","HARDLY","HATE","HAVE","HE","HEAD","HEALTH","HEAR","HEART","HEAT","HEAVY",
"HELL","HELP","HENCE","HER","HERE","HERSELF","HIDE","HIGH","HIGHLY","HILL","HIM","HIMSELF","HIS",
"HISTORICAL","HISTORY","HIT","HOLD","HOLE","HOLIDAY","HOME","HOPE","HORSE","HOSPITAL","HOT","HOTEL",
"HOUR","HOUSE","HOUSEHOLD","HOUSING","HOW","HOWEVER","HUGE","HUMAN","HURT","HUSBAND","I","IDEA",
"IDENTIFY","IF","IGNORE","ILLUSTRATE","IMAGE","IMAGINE","IMMEDIATE","IMMEDIATELY","IMPACT",
"IMPLICATION","IMPLY","IMPORTANCE","IMPORTANT","IMPOSE","IMPOSSIBLE","IMPRESSION","IMPROVE",
"IMPROVEMENT","IN","INCIDENT","INCLUDE","INCLUDING","INCOME","INCREASE","INCREASED","INCREASINGLY",
"INDEED","INDEPENDENT","INDEX","INDICATE","INDIVIDUAL","INDUSTRIAL","INDUSTRY","INFLUENCE",
"INFORM","INFORMATION","INITIAL","INITIATIVE","INJURY","INSIDE","INSIST","INSTANCE","INSTEAD",
"INSTITUTE","INSTITUTION","INSTRUCTION","INSTRUMENT","INSURANCE","INTEND","INTENTION","INTEREST",
"INTERESTED","INTERESTING","INTERNAL","INTERNATIONAL","INTERPRETATION","INTERVIEW","INTO","INTRODUCE",
"INTRODUCTION","INVESTIGATE","INVESTIGATION","INVESTMENT","INVITE","INVOLVE","IRON","IS","ISLAND",
"ISSUE","IT","ITEM","ITS","ITSELF","JOB","JOIN","JOINT","JOURNEY","JUDGE","JUMP","JUST","JUSTICE",
"KEEP","KEY","KID","KILL","KIND","KING","KITCHEN","KNEE","KNOW","KNOWLEDGE","LABOUR","LACK",
"LADY","LAND","LANGUAGE","LARGE","LARGELY","LAST","LATE","LATER","LATTER","LAUGH","LAUNCH",
"LAW","LAWYER","LAY","LEAD","LEADER","LEADERSHIP","LEADING","LEAF","LEAGUE","LEAN","LEARN",
"LEAST","LEAVE","LEFT","LEG","LEGAL","LEGISLATION","LENGTH","LESS","LET","LETTER","LEVEL","LIABILITY",
"LIBERAL","LIBRARY","LIE","LIFE","LIFT","LIGHT","LIKE","LIKELY","LIMIT","LIMITED","LINE","LINK","LIP",
"LIST","LISTEN","LITERATURE","LITTLE","LIVE","LIVING","LOAN","LOCAL","LOCATION","LONG","LOOK","LORD",
"LOSE","LOSS","LOT","LOVE","LOVELY","LOW","LUNCH","MACHINE","MAGAZINE","MAIN","MAINLY","MAINTAIN",
"MAJOR","MAJORITY","MAKE","MALE","MAN","MANAGE","MANAGEMENT","MANAGER","MANNER","MANY","MAP","MARK",
"MARKET","MARRIAGE","MARRIED","MARRY","MASS","MASTER","MATCH","MATERIAL","MATTER","MAY","MAYBE",
"ME","MEAL","MEAN","MEANING","MEANS","MEANWHILE","MEASURE","MECHANISM","MEDIA","MEDICAL","MEET",
"MEETING","MEMBER","MEMBERSHIP","MEMORY","MENTAL","MENTION","MERELY","MESSAGE","METAL","METHOD",
"MIDDLE","MIGHT","MILE","MILITARY","MILK","MIND","MINE","MINISTER","MINISTRY","MINUTE","MISS",
"MISTAKE","MODEL","MODERN","MODULE","MOMENT","MONEY","MONTH","MORE","MORNING","MOST","MOTHER",
"MOTION","MOTOR","MOUNTAIN","MOUTH","MOVE","MOVEMENT","MUCH","MURDER","MUSEUM","MUSIC","MUST",
"MY","MYSELF","NAME","NARROW","NATION","NATIONAL","NATURAL","NATURE","NEAR","NEARLY","NECESSARILY",
"NECESSARY","NECK","NEED","NEGOTIATION","NEIGHBOUR","NEITHER","NETWORK","NEVER","NEVERTHELESS","NEW",
"NEWS","NEWSPAPER","NEXT","NICE","NIGHT","NO","NOBODY","NOD","NOISE","NONE","NOR","NORMAL","NORMALLY",
"NORTH","NORTHERN","NOSE","NOT","NOTE","NOTHING","NOTICE","NOTION","NOW","NUCLEAR","NUMBER","NURSE",
"OBJECT","OBJECTIVE","OBSERVATION","OBSERVE","OBTAIN","OBVIOUS","OBVIOUSLY","OCCASION","OCCUR","ODD",
"OF","OFF","OFFENCE","OFFER","OFFICE","OFFICER","OFFICIAL","OFTEN","OIL","OKAY","OLD","ON","ONCE",
"ONE","ONLY","ONTO","OPEN","OPERATE","OPERATION","OPINION","OPPORTUNITY","OPPOSITION","OPTION","OR",
"ORDER","ORDINARY","ORGANISATION","ORGANISE","ORGANIZATION","ORIGIN","ORIGINAL","OTHER","OTHERWISE",
"OUGHT","OUR","OURSELVES","OUT","OUTCOME","OUTPUT","OUTSIDE","OVER","OVERALL","OWN","OWNER","PACKAGE",
"PAGE","PAIN","PAINT","PAINTING","PAIR","PANEL","PAPER","PARENT","PARK","PARLIAMENT","PART","PARTICULAR",
"PARTICULARLY","PARTLY","PARTNER","PARTY","PASS","PASSAGE","PAST","PATH","PATIENT","PATTERN","PAY",
"PAYMENT","PEACE","PENSION","PEOPLE","PER","PERCENT","PERFECT","PERFORM","PERFORMANCE","PERHAPS",
"PERIOD","PERMANENT","PERSON","PERSONAL","PERSUADE","PHASE","PHONE","PHOTOGRAPH","PHYSICAL","PICK",
"PICTURE","PIECE","PLACE","PLAN","PLANNING","PLANT","PLASTIC","PLATE","PLAY","PLAYER","PLEASE",
"PLEASURE","PLENTY","PLUS","POCKET","POINT","POLICE","POLICY","POLITICAL","POLITICS","POOL","POOR",
"POPULAR","POPULATION","POSITION","POSITIVE","POSSIBILITY","POSSIBLE","POSSIBLY","POST","POTENTIAL",
"POUND","POWER","POWERFUL","PRACTICAL","PRACTICE","PREFER","PREPARE","PRESENCE","PRESENT","PRESIDENT",
"PRESS","PRESSURE","PRETTY","PREVENT","PREVIOUS","PREVIOUSLY","PRICE","PRIMARY","PRIME","PRINCIPLE",
"PRIORITY","PRISON","PRISONER","PRIVATE","PROBABLY","PROBLEM","PROCEDURE","PROCESS","PRODUCE","PRODUCT",
"PRODUCTION","PROFESSIONAL","PROFIT","PROGRAM","PROGRAMME","PROGRESS","PROJECT","PROMISE","PROMOTE",
"PROPER","PROPERLY","PROPERTY","PROPORTION","PROPOSE","PROPOSAL","PROSPECT","PROTECT","PROTECTION",
"PROVE","PROVIDE","PROVIDED","PROVISION","PUB","PUBLIC","PUBLICATION","PUBLISH","PULL","PUPIL",
"PURPOSE","PUSH","PUT","QUALITY","QUARTER","QUESTION","QUICK","QUICKLY","QUIET","QUITE","RACE",
"RADIO","RAILWAY","RAIN","RAISE","RANGE","RAPIDLY","RARE","RATE","RATHER","REACH","REACTION",
"READ","READER","READING","READY","REAL","REALISE","REALITY","REALIZE","REALLY","REASON","REASONABLE",
"RECALL","RECEIVE","RECENT","RECENTLY","RECOGNISE","RECOGNITION","RECOGNIZE","RECOMMEND","RECORD",
"RECOVER","RED","REDUCE","REDUCTION","REFER","REFERENCE","REFLECT","REFORM","REFUSE","REGARD","REGION",
"REGIONAL","REGULAR","REGULATION","REJECT","RELATE","RELATION","RELATIONSHIP","RELATIVE","RELATIVELY",
"RELEASE","RELEVANT","RELIEF","RELIGION","RELIGIOUS","RELY","REMAIN","REMEMBER","REMIND","REMOVE",
"REPEAT","REPLACE","REPLY","REPORT","REPRESENT","REPRESENTATION","REPRESENTATIVE","REQUEST","REQUIRE",
"REQUIREMENT","RESEARCH","RESOURCE","RESPECT","RESPOND","RESPONSE","RESPONSIBILITY","RESPONSIBLE",
"REST","RESTAURANT","RESULT","RETAIN","RETURN","REVEAL","REVENUE","REVIEW","REVOLUTION","RICH","RIDE",
"RIGHT","RING","RISE","RISK","RIVER","ROAD","ROCK","ROLE","ROLL","ROOF","ROOM","ROUND","ROUTE","ROW",
"ROYAL","RULE","RUN","RURAL","SAFE","SAFETY","SALE","SAME","SAMPLE","SATISFY","SAVE","SAY","SCALE",
"SCENE","SCHEME","SCHOOL","SCIENCE","SCIENTIFIC","SCIENTIST","SCORE","SCREEN","SEA","SEARCH","SEASON",
"SEAT","SECOND","SECONDARY","SECRETARY","SECTION","SECTOR","SECURE","SECURITY","SEE","SEEK","SEEM",
"SELECT","SELECTION","SELL","SEND","SENIOR","SENSE","SENTENCE","SEPARATE","SEQUENCE","SERIES","SERIOUS",
"SERIOUSLY","SERVANT","SERVE","SERVICE","SESSION","SET","SETTLE","SETTLEMENT","SEVERAL","SEVERE","SEX",
"SEXUAL","SHAKE","SHALL","SHAPE","SHARE","SHE","SHEET","SHIP","SHOE","SHOOT","SHOP","SHORT","SHOT","SHOULD",
"SHOULDER","SHOUT","SHOW","SHUT","SIDE","SIGHT","SIGN","SIGNAL","SIGNIFICANCE","SIGNIFICANT","SILENCE",
"SIMILAR","SIMPLE","SIMPLY","SINCE","SING","SINGLE","SIR","SISTER","SIT","SITE","SITUATION","SIZE","SKILL",
"SKIN","SKY","SLEEP","SLIGHTLY","SLIP","SLOW","SLOWLY","SMALL","SMILE","SO","SOCIAL","SOCIETY","SOFT",
"SOFTWARE","SOIL","SOLDIER","SOLICITOR","SOLUTION","SOME","SOMEBODY","SOMEONE","SOMETHING","SOMETIMES",
"SOMEWHAT","SOMEWHERE","SON","SONG","SOON","SORRY","SORT","SOUND","SOURCE","SOUTH","SOUTHERN","SPACE",
"SPEAK","SPEAKER","SPECIAL","SPECIES","SPECIFIC","SPEECH","SPEED","SPEND","SPIRIT","SPORT","SPOT","SPREAD",
"SPRING","STAFF","STAGE","STAND","STANDARD","STAR","START","STATE","STATEMENT","STATION","STATUS",
"STAY","STEAL","STEP","STICK","STILL","STOCK","STONE","STOP","STORE","STORY","STRAIGHT","STRANGE",
"STRATEGY","STREET","STRENGTH","STRIKE","STRONG","STRONGLY","STRUCTURE","STUDENT","STUDIO","STUDY",
"STUFF","STYLE","SUBJECT","SUBSTANTIAL","SUCCEED","SUCCESS","SUCCESSFUL","SUCH","SUDDENLY","SUFFER",
"SUFFICIENT","SUGGEST","SUGGESTION","SUITABLE","SUM","SUMMER","SUN","SUPPLY","SUPPORT","SUPPOSE",
"SURE","SURELY","SURFACE","SURPRISE","SURROUND","SURVEY","SURVIVE","SWITCH","SYSTEM","TABLE","TAKE",
"TALK","TALL","TAPE","TARGET","TASK","TAX","TEA","TEACH","TEACHER","TEACHING","TEAM","TEAR","TECHNICAL",
"TECHNIQUE","TECHNOLOGY","TELEPHONE","TELEVISION","TELL","TEMPERATURE","TEND","TERM","TERMS","TERRIBLE",
"TEST","TEXT","THAN","THANK","THANKS","THAT","THE","THEATRE","THEIR","THEM","THEME","THEMSELVES",
"THEN","THEORY","THERE","THEREFORE","THESE","THEY","THIN","THING","THINK","THIS","THOSE","THOUGH",
"THOUGHT","THREAT","THREATEN","THROUGH","THROUGHOUT","THROW","THUS","TICKET","TIME","TINY","TITLE",
"TO","TODAY","TOGETHER","TOMORROW","TONE","TONIGHT","TOO","TOOL","TOOTH","TOP","TOTAL","TOTALLY",
"TOUCH","TOUR","TOWARDS","TOWN","TRACK","TRADE","TRADITION","TRADITIONAL","TRAFFIC","TRAIN","TRAINING",
"TRANSFER","TRANSPORT","TRAVEL","TREAT","TREATMENT","TREATY","TREE","TREND","TRIAL","TRIP","TROOP",
"TROUBLE","TRUE","TRUST","TRUTH","TRY","TURN","TWICE","TYPE","TYPICAL","UNABLE","UNDER","UNDERSTAND",
"UNDERSTANDING","UNDERTAKE","UNEMPLOYMENT","UNFORTUNATELY","UNION","UNIT","UNITED","UNIVERSITY","UNLESS",
"UNLIKELY","UNTIL","UP","UPON","UPPER","URBAN","US","USE","USED","USEFUL","USER","USUAL","USUALLY",
"VALUE","VARIATION","VARIETY","VARIOUS","VARY","VAST","VEHICLE","VERSION","VERY","VIA","VICTIM",
"VICTORY","VIDEO","VIEW","VILLAGE","VIOLENCE","VISION","VISIT","VISITOR","VITAL","VOICE","VOLUME",
"VOTE","WAGE","WAIT","WALK","WALL","WANT","WAR","WARM","WARN","WASH","WATCH","WATER","WAVE","WAY",
"WE","WEAK","WEAPON","WEAR","WEATHER","WEEK","WEEKEND","WEIGHT","WELCOME","WELFARE","WELL","WEST",
"WESTERN","WHAT","WHATEVER","WHEN","WHERE","WHEREAS","WHETHER","WHICH","WHILE","WHILST","WHITE",
"WHO","WHOLE","WHOM","WHOSE","WHY","WIDE","WIDELY","WIFE","WILD","WILL","WIN","WIND","WINDOW",
"WINE","WING","WINNER","WINTER","WISH","WITH","WITHDRAW","WITHIN","WITHOUT","WOMAN","WONDER",
"WONDERFUL","WOOD","WORD","WORK","WORKER","WORKING","WORKS","WORLD","WORRY","WORTH","WOULD",
"WRITE","WRITER","WRITING","WRONG","YARD","YEAH","YEAR","YES","YESTERDAY","YET","YOU","YOUNG",
"YOUR","YOURSELF","YOUTH"};

        int[] SankakuSuuArr = DeriveSankakuSuuArr();

        int AnswerCnt = 0;
        foreach (string EachTango in TangoArr) {
            if (Array.BinarySearch<int>(SankakuSuuArr, DeriveTangoVal(EachTango)) >= 0) {
                Console.WriteLine("{0}は三角語です。現在の三角語の数={1}", EachTango,++AnswerCnt);
            }
        }
    }

    //三角数の最大値以下の三角数の配列を返す
    static int[] DeriveSankakuSuuArr()
    {
        var WillReturnList = new List<int>();

        for (int n = 1; n < int.MaxValue; n++) {
            int wkVal = n * (n + 1) / 2;
            if (wkVal > MaxSankakuVal) break;
            WillReturnList.Add(wkVal);
        }
        return WillReturnList.ToArray();
    }

    //単語の値を求める
    static int DeriveTangoVal(string pTango)
    {
        int TangoVal = 0;
        foreach (char EachChar in pTango) {
            TangoVal += EachChar - 'A' + 1;
        }
        return TangoVal;
    }
}


実行結果

TRAVELは三角語です。現在の三角語の数=147
TYPEは三角語です。現在の三角語の数=148
UNABLEは三角語です。現在の三角語の数=149
UNDERSTANDは三角語です。現在の三角語の数=150
UPONは三角語です。現在の三角語の数=151
USEは三角語です。現在の三角語の数=152
VARIOUSは三角語です。現在の三角語の数=153
VARYは三角語です。現在の三角語の数=154
VIDEOは三角語です。現在の三角語の数=155
WAGEは三角語です。現在の三角語の数=156
WARMは三角語です。現在の三角語の数=157
WATCHは三角語です。現在の三角語の数=158
WEは三角語です。現在の三角語の数=159
WHILSTは三角語です。現在の三角語の数=160
WIDELYは三角語です。現在の三角語の数=161
WOMANは三角語です。現在の三角語の数=162


解説

三角数の配列を用意しておいて、
ArrayのBinarySearchジェネリックメソッドで、三角数かを判定してます。