Project Euler problem 68

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <set>
#include <vector>
#include <map>
#define MAXN 111
#define MAXM 55555
#define INF 1000000007
using namespace std;
int a[12];
int sum[6];
string ans, tmp;
int main()
{
int n = 10;
int first = 1;
ans = "", tmp = "";
for(int i = 1; i <= n; i++) a[i] = i;
do {
int pos = 1;
for(int i = 1; i <= 5; i++) {
if(a[i] < a[pos]) pos = i;
int z = i + 6;
if(z > 10) z = z - 5;
sum[i] = a[i] + a[i + 5] + a[z];
}
if(pos != 1) continue;
int flag = 1;
for(int i = 2; i <= 5; i++)
if(sum[i] != sum[i - 1]) flag = 0;
if(sum[1] != sum[5]) flag = 0;
for(int i = 6; i <= 10; i++) {
if(a[i] == 10) flag = 0;
}
tmp = "";
if(flag) {
for(int i = 1; i <= 5; i++) {
int z = i + 6;
if(z > 10) z = z - 5;
tmp += (a[i] + 'a');
tmp += (a[i + 5] + 'a');
tmp += (a[z] + 'a');
}
if(!first) {
if(ans < tmp) ans = tmp;
} else {
ans = tmp;
first = 1;
}

}
}while(next_permutation(a + 1, a + n + 1));
for(int i = 0; i < 15; i++) printf("%d", ans[i] - 'a');
return 0;
}