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problem_008.c
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problem_008.c
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// -*- compile-command: "gcc -std=c99 -o problem_008 problem_008.c ceuler.c -Wall -lm" -*-
// Copyright (c) 2014 Michael Caldwell
#include <stdio.h>
#include "ceuler.h"
int main()
{
char bignum[1000]="7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450";
printf("Project Euler - Problem 8:\n"
"Find the thirteen adjacent digits in the 1000-digit number that have the greatest product.\n"
"What is the value of this product?\n\n%s\n\n", bignum);
// Begin time tracking
struct timeval start;
gettimeofday(&start, NULL);
unsigned long long largest = 0, candidate = 1;
const int adjacentSize = 13;
for (int numIndex = 0 ; numIndex <= (1000-adjacentSize) ; numIndex++)
{
candidate = 1;
for (int adjacentIndex = 0 ; adjacentIndex < adjacentSize ; adjacentIndex++)
{
candidate = candidate * (bignum[numIndex + adjacentIndex] - '0');
}
if (candidate > largest)
largest = candidate;
}
printf("Greatest product: %llu\n", largest);
printElapsedTime(start);
return 0;
}