拓扑排序

添加链接描述

思路

建图，输出图的拓扑序

code

#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
const int N = 205;
int n, m;
int main()
{
    cin >> n;
    while(n--)
    {
        string str1, str2;
        map<string, int> in;
        map<string, vector<string>> mp;
        set<string> se;
        cin >> m;
        for(int i = 1; i <= m; i++)
        {
            cin >> str1 >> str2;
            se.insert(str1), se.insert(str2);
            mp[str1].push_back(str2);
            in[str2]++;
        }
        queue<string> q;
        for(set<string>::iterator it = se.begin(); it != se.end(); it++)
            if(in[(*it)] == 0)
                q.push((*it));
        while(q.size())
        {
            string x = q.front();
            q.pop();
            cout << x << " ";
            for(vector<string>::iterator it = mp[x].begin(); it != mp[x].end(); it++)
            {
                in[(*it)]--;
                if(in[(*it)] == 0)
                    q.push((*it));
            }
        }
        cout << '\n';
    }
    return 0;
}