[leetcode]785. Is Graph Bipartite?

[leetcode]785. Is Graph Bipartite?

---

Analysis

出太阳啦~—— [每天刷题并不难0.0]

Given an undirected graph, return true if and only if it is bipartite.
Recall that a graph is bipartite if we can split it’s set of nodes into two independent subsets A and B such that every edge in the graph has one node in A and another node in B.
The graph is given in the following form: graph[i] is a list of indexes j for which the edge between nodes i and j exists. Each node is an integer between 0 and graph.length - 1. There are no self edges or parallel edges: graph[i] does not contain i, and it doesn’t contain any element twice.

Explanation:

判断给定的图是否是二分图，用染色法解决

Implement

class Solution {
public:
    bool isBipartite(vector<vector<int>>& graph) {
        int n = graph.size();
        vector<int> color(n, 0);
        for(int i=0; i<n; i++){
            if(color[i] == 0){
                if(!dfs(graph, color, i, 1))
                    return false;
            }
        }
        return true;
    }
    bool dfs(vector<vector<int>>& graph, vector<int>& color, int node, int c){
        color[node] = c;
        for(int i=0; i<graph[node].size(); i++){
            if(color[graph[node][i]] == c)
                return false;
            if(color[graph[node][i]] == 0 && !dfs(graph, color, graph[node][i], -c))
                return false;
        }
        return true;
    }
};