用c++代码实现。Arbitrage is the use of discrepancies in currency exchange rates to transform one unit of a currency into more than one unit of the same currency. For example, suppose that 1 US Dollar buys 0.5 British pound, 1 British pound buys 10.0 French fran

以下是C++代码实现：

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

const int N = 210;

int n, m;
double dist[N][N];

int main() {
    while (cin >> n, n) {
        memset(dist, 0, sizeof dist); // 初始化
        for (int i = 1; i <= n; i++) {
            dist[i][i] = 1; // 自己到自己的汇率为1
        }
        cin >> m;
        for (int i = 0; i < m; i++) {
            int a, b;
            double c;
            cin >> a >> b >> c;
            dist[a][b] = c; // 记录汇率
        }
        // Floyd算法求最短路
        for (int k = 1; k <= n; k++) {
            for (int i = 1; i <= n; i++) {
                for (int j = 1; j <= n; j++) {
                    dist[i][j] = max(dist[i][j], dist[i][k] * dist[k][j]);
                }
            }
        }
        bool flag = false;
        for (int i = 1; i <= n; i++) {
            if (dist[i][i] > 1) { // 存在套汇机会
                flag = true;
                break;
            }
        }
        if (flag)
            cout << "Yes" << endl;
        else
            cout << "No" << endl;
    }
    return 0;
}

思路：使用Floyd算法求解任意两个货币之间的汇率，然后检查是否存在套汇机会。若存在，则输出"Yes"，否则输出"No"。