任意两个城市之间最短路（Floyd）

#include <iostream>#include <cstdlib>#include <string>#include <cstdio>#include <fstream>using namespace std;const int maxn = 100;int Hash(string s, string h[], int &num, int Match[]){    int now = 0;    for (int i = 0; ; i++) {        now = (s[0] - 'A' + i) % maxn;        if (h[now] == "") {//如果没有被Hash过，就新建            h[now] = s;            Match[num] = now;            num++;            return now;        } else if (h[now] == s) {//如果被Hash过，就直接返回原来Hash出来的地址            return now;        }    }}void Floyd(){}int main(){    ifstream in("in.txt");    for (int i = 0; i < 4; i++) {        string s;        in >> s;    }    string h[maxn] = "";    string s1, s2;    int path[maxn][maxn];    for (int i = 0; i < maxn; i++) {        for (int j = 0; j < maxn; j++) {            path[i][j] = -1;        }    }    int cost, dis;    int cnt = 0;    int num = 0;    int Match[maxn];    while (in >> s1 >> s2 >> cost >> dis) {        cnt++;        int u = Hash (s1, h, num, Match);        int v = Hash (s2, h, num, Match);        path[u][v] = dis;        path[v][u] = dis;    }    in.close();    for (int k = 0; k <= num; k++) {        for (int i = 0; i <= num; i++) {            for (int j = 0; j <= num; j++) {                int a1 = Match[k], a2 = Match[i], a3 = Match[j];                if ((path[a2][a1] != -1 && path[a1][a3] != -1) && (path[a2][a1] + path[a1][a3] < path[a2][a3] || path[a2][a3] == -1)) {                    path[a2][a3] = path[a2][a1] + path[a1][a3];                }            }        }    }    int op;    while (1) {        cout << "如果想继续得到城市间的最短距离，请输入1，如果想要退出程序，请输入0" << endl;        cin >> op;        if (op == 0) break;        cout << "请输入想要得到最短路的两个城市的名称，用空格隔开（请保证这两个城市的名称和文件中文件的名称一样）" << endl;        cin >> s1 >> s2;        int i = Hash (s1, h, num, Match), j = Hash (s2, h, num, Match);        if (path[i][j] == -1) {            cout << "抱歉，这两个城市之间没有路径到达" << endl;        } else {            cout << "两个城市之间最短距离为：" << path[i][j] << endl;        }    }    return 0;}