UVA 436 - Arbitrage (II)（floyd)

UVA 436 - Arbitrage (II)

题目链接

题意：给定一些国家货币的汇率，问能否通过不断换货币使钱得到增长

思路：floyd，完事后判断一下有没有连到自己能大于1的情况

代码：

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

const int N = 35;

int n;
double g

;
map<string, int> hash;

int main() {
int cas = 0;
while (~scanf("%d", &n) && n) {
string a, b;
hash.clear();
for (int i = 1; i <= n; i++) {
cin >> a;
hash[a] = i;
}
int m;
double f;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (i == j) g[i][j] = 1.0;
else g[i][j] = 0;
}
}
scanf("%d", &m);
while (m--) {
cin >> a >> f >> b;
int u = hash[a], v = hash[b];
g[u][v] = f;
}
for (int k = 1; k <= n; k++) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++)
g[i][j] = max(g[i][j], g[i][k] * g[k][j]);
}
}
printf("Case %d: ", ++cas);
int flag = 1;
for (int i = 1; i <= n; i++) {
if (g[i][i] > 1.0) {
printf("Yes\n");
flag = 0;
break;
}
}
if (flag) printf("No\n");
}
return 0;
}