leetcode 785 染色法判断二分图

class Solution {
public:
    bool isBipartite(vector<vector<int>>& graph) {
        int n=graph.size();
        vector<int>G[n],f(n,0);
        for(int i=0;i<n;i++)
        for(auto &p:graph[i])G[i].push_back(p);
        function<int(int,int)>dfs=[&](int u,int c)
        {
            f[u]=c;
            for(auto &v:G[u])
            {
                if(f[v]==c)return 0;
                if(!f[v]&&!dfs(v,3-c))return 0; 
            }
            return 1;
        };
        for(int i=0;i<n;i++)
        if(!f[i])if(!dfs(i,1))return false;
        return true;
    }
};