project-euler/problem013/solution.cxx at master · kmandrika/project-euler · GitHub

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#include <iostream>
#include <string>
#include <algorithm>

const char* numbers[] = {
        "37107287533902102798797998220837590246510135740250"
      , "46376937677490009712648124896970078050417018260538"
      , "74324986199524741059474233309513058123726617309629"
      , "91942213363574161572522430563301811072406154908250"
      , "23067588207539346171171980310421047513778063246676"
      , "89261670696623633820136378418383684178734361726757"
      , "28112879812849979408065481931592621691275889832738"
      , "44274228917432520321923589422876796487670272189318"
      , "47451445736001306439091167216856844588711603153276"
      , "70386486105843025439939619828917593665686757934951"
      , "62176457141856560629502157223196586755079324193331"
      , "64906352462741904929101432445813822663347944758178"
      , "92575867718337217661963751590579239728245598838407"
      , "58203565325359399008402633568948830189458628227828"
      , "80181199384826282014278194139940567587151170094390"
      , "35398664372827112653829987240784473053190104293586"
      , "86515506006295864861532075273371959191420517255829"
      , "71693888707715466499115593487603532921714970056938"
      , "54370070576826684624621495650076471787294438377604"
      , "53282654108756828443191190634694037855217779295145"
      , "36123272525000296071075082563815656710885258350721"
      , "45876576172410976447339110607218265236877223636045"
      , "17423706905851860660448207621209813287860733969412"
      , "81142660418086830619328460811191061556940512689692"
      , "51934325451728388641918047049293215058642563049483"
      , "62467221648435076201727918039944693004732956340691"
      , "15732444386908125794514089057706229429197107928209"
      , "55037687525678773091862540744969844508330393682126"
      , "18336384825330154686196124348767681297534375946515"
      , "80386287592878490201521685554828717201219257766954"
      , "78182833757993103614740356856449095527097864797581"
      , "16726320100436897842553539920931837441497806860984"
      , "48403098129077791799088218795327364475675590848030"
      , "87086987551392711854517078544161852424320693150332"
      , "59959406895756536782107074926966537676326235447210"
      , "69793950679652694742597709739166693763042633987085"
      , "41052684708299085211399427365734116182760315001271"
      , "65378607361501080857009149939512557028198746004375"
      , "35829035317434717326932123578154982629742552737307"
      , "94953759765105305946966067683156574377167401875275"
      , "88902802571733229619176668713819931811048770190271"
      , "25267680276078003013678680992525463401061632866526"
      , "36270218540497705585629946580636237993140746255962"
      , "24074486908231174977792365466257246923322810917141"
      , "91430288197103288597806669760892938638285025333403"
      , "34413065578016127815921815005561868836468420090470"
      , "23053081172816430487623791969842487255036638784583"
      , "11487696932154902810424020138335124462181441773470"
      , "63783299490636259666498587618221225225512486764533"
      , "67720186971698544312419572409913959008952310058822"
      , "95548255300263520781532296796249481641953868218774"
      , "76085327132285723110424803456124867697064507995236"
      , "37774242535411291684276865538926205024910326572967"
      , "23701913275725675285653248258265463092207058596522"
      , "29798860272258331913126375147341994889534765745501"
      , "18495701454879288984856827726077713721403798879715"
      , "38298203783031473527721580348144513491373226651381"
      , "34829543829199918180278916522431027392251122869539"
      , "40957953066405232632538044100059654939159879593635"
      , "29746152185502371307642255121183693803580388584903"
      , "41698116222072977186158236678424689157993532961922"
      , "62467957194401269043877107275048102390895523597457"
      , "23189706772547915061505504953922979530901129967519"
      , "86188088225875314529584099251203829009407770775672"
      , "11306739708304724483816533873502340845647058077308"
      , "82959174767140363198008187129011875491310547126581"
      , "97623331044818386269515456334926366572897563400500"
      , "42846280183517070527831839425882145521227251250327"
      , "55121603546981200581762165212827652751691296897789"
      , "32238195734329339946437501907836945765883352399886"
      , "75506164965184775180738168837861091527357929701337"
      , "62177842752192623401942399639168044983993173312731"
      , "32924185707147349566916674687634660915035914677504"
      , "99518671430235219628894890102423325116913619626622"
      , "73267460800591547471830798392868535206946944540724"
      , "76841822524674417161514036427982273348055556214818"
      , "97142617910342598647204516893989422179826088076852"
      , "87783646182799346313767754307809363333018982642090"
      , "10848802521674670883215120185883543223812876952786"
      , "71329612474782464538636993009049310363619763878039"
      , "62184073572399794223406235393808339651327408011116"
      , "66627891981488087797941876876144230030984490851411"
      , "60661826293682836764744779239180335110989069790714"
      , "85786944089552990653640447425576083659976645795096"
      , "66024396409905389607120198219976047599490197230297"
      , "64913982680032973156037120041377903785566085089252"
      , "16730939319872750275468906903707539413042652315011"
      , "94809377245048795150954100921645863754710598436791"
      , "78639167021187492431995700641917969777599028300699"
      , "15368713711936614952811305876380278410754449733078"
      , "40789923115535562561142322423255033685442488917353"
      , "44889911501440648020369068063960672322193204149535"
      , "41503128880339536053299340368006977710650566631954"
      , "81234880673210146739058568557934581403627822703280"
      , "82616570773948327592232845941706525094512325230608"
      , "22918802058777319719839450180888072429661980811197"
      , "77158542502016545090413245809786882778948721859617"
      , "72107838435069186155435662884062257473692284509516"
      , "20849603980134001723930671666823555245252804609722"
      , "53503534226472524250874054075591789781264330331690"
};

//! too bad c++03 doesn't support rvalue references
std::string problem13(const char* numbers[], size_t digits, size_t count)
{
        std::string result;

	unsigned int carry = 0;

	while (digits--) {
	        unsigned int sum_of_ith_digits = carry;

		for (unsigned int i = 0; i < count; ++i)
		        sum_of_ith_digits += numbers[i][digits] - 48;

		carry = sum_of_ith_digits / 10;
		result.append(1, static_cast<char>(sum_of_ith_digits % 10 + 48));
	}

	//! this would need to take care of the case where carry is > 100,
	//  but, as it turns out, in _this_ case, carry is < 100.
	result.append(1, static_cast<char>(carry % 10 + 48));
	result.append(1, static_cast<char>(carry / 10 + 48));
	result.append(1, '\0');

	std::reverse(result.begin(), result.end());

	return result.substr(1, 10);
}

int main(int argc, char* argv[])
{
        std::cout<<problem13(numbers, 50, sizeof numbers / sizeof (numbers[0]))<<std::endl;
}