POJ 2240 Arbitrage

#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<iostream>
#include<vector>
#include<map>
using namespace std;

int N, M;
char name[110];
map<string, int> mp;
double maze[1010][1010];

void floyd() {
    for(int k = 1; k <= N; k ++) {
        for(int i = 1; i <= N; i ++) {
            for(int j = 1; j <= N; j ++) {
                if(maze[i][j] < maze[i][k] * maze[k][j])
                    maze[i][j] = maze[i][k] * maze[k][j];
            }
        }
    }
}

int main() {
    int Case = 1;
    char s1[110], s2[110];
    double cost;
    while(~scanf("%d", &N)) {
        if(!N) break;
        memset(maze, 0, sizeof(maze));
        for(int i = 1; i <= N; i ++)
            maze[i][i] = 1;

        for(int i = 1; i <= N; i ++) {
            scanf("%s", name);
            mp[name] = i;
        }
        scanf("%d", &M);
        for(int i = 1; i <= M; i ++) {
            scanf("%s%lf%s", s1, &cost, s2);
            maze[mp[s1]][mp[s2]] = cost;
        }

        floyd();
        printf("Case %d: ", Case ++);

        for(int i = 1; i <= N; i ++) {
            if(maze[i][i] > 1) {
                printf("Yes\n");
                break;
            }
            else if(i == N)
                printf("No\n");
        }
    }
    return 0;
}