# 1466. Reorder Routes to Make All Paths Lead to the City Zero
###### tags: `LeetCode`
## **Link**
https://leetcode.com/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero/
## **Code**

class Solution {
public:
    void solve(vector<vector<pair<int,int>>> &edge, vector<int> &visited, queue<int> &qee, int &ans)
    {
        int idx=qee.front();
        visited[idx]=1;
        qee.pop();
        for(pair<int,int> &pii:edge[idx])
        {
            if(visited[pii.first]==0)
            {
                visited[pii.first]=1;
                ans+=pii.second;
                qee.push(pii.first);
            }
        }
    }
    int minReorder(int n, vector<vector<int>>& connections) 
    {
        int ans=0;
        vector<int> visited(n,0);
        vector<vector<pair<int,int>>> edge(n,vector<pair<int,int>>());
        for(vector<int> &vt:connections)
        {
            edge[vt[0]].push_back(make_pair(vt[1],1));
            edge[vt[1]].push_back(make_pair(vt[0],0));
        }
        queue<int> qee;
        qee.push(0);
        while(!qee.empty())
            solve(edge,visited,qee,ans);
        return ans;
    }
};

## date
**2023.03.24**

{%hackmd @nnks8908/background_leetcode %}