785 染色问题

Author: LuYanFCP

README.md

@@ -14,6 +14,7 @@ Leetcode刷题记录
 + No.46 [python](python/46.py)
 + No.126 [cpp](cpp/126.cpp) [python](python/126.py)
 + No.543 [cpp](cpp/543.cpp) [python](python/543.py)
++ No.785 [cpp-dfs](cpp/785.cpp) [cpp-bfs](cpp/785-bfs.cpp)  **二分图染色问题**
 
 ### 并查集
 
@@ -65,7 +66,7 @@ Leetcode刷题记录
 + No.63 [cpp](cpp/63.cpp) [python](python/63.py)
 + No.70 [cpp](cpp/70.cpp) [python](python/70.py)   easy
 + No.53 [cpp](cpp/53.cpp) [python](python/53.py)
-+ No.96 [cpp](cpp/96.cpp) [python](python/96.py)   [java](java\Problem96.java)  easy
++ No.96 [cpp](cpp/96.cpp) [python](python/96.py) easy
 + No.120 [cpp](cpp/120.cpp) [python](python/120.py)
 + No.837 [cpp](cpp/837.cpp) [python](python/837.py)
 + No.126 [cpp](cpp/126.cpp) [python](python/126.py)

cpp/785-bfs.cpp

@@ -0,0 +1,32 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution {
+public:
+    bool isBipartite(vector<vector<int>>& graph) {
+        size_t n = graph.size();
+        vector<int> visited(n, 0);
+        for (int i = 0; i < n; ++i) {
+            if (visited[i] == 0 && !bfs(graph, visited, i)) return false;
+        }
+        return true;
+    }
+    bool bfs(vector<vector<int>>& graph, vector<int> &visited, int begin_node) {
+        queue<int> q;
+        q.push(begin_node);
+        visited[begin_node] = 1;
+        while (!q.empty()) {
+            int node = q.front();
+            q.pop();
+            int color = visited[node];
+            for (int node_i: graph[node]) {
+                if (visited[node_i] != 0) {
+                    if (visited[node_i] != -color) return false;
+                } else {
+                    visited[node_i] = -color;
+                    q.push(node_i);
+                }
+            }
+        }
+        return true;
+    }
+};

cpp/785.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Solution {
+public:
+    bool isBipartite(vector<vector<int>>& graph) {
+        int n = graph.size();
+        vector<int> visited(n, 0);
+        for (int i = 0; i < n; ++i) {
+            if (visited[i] == 0  &&  !dfs(graph, visited, 1, i) ) {
+                return false;
+            }
+        }
+        return true;
+    }
+    bool dfs(vector<vector<int>>& graph, vector<int> &visited, int color, int node) {
+        if (visited[node] != 0) {// 被访问过 {
+            return visited[node] == color;
+        }
+        visited[node] = color;
+        for (int node_i : graph[node])
+            if (!dfs(graph, visited, -color, node_i)) return false;
+        return true;
+    }
+};
+
+int main(int argc, char const *argv[])
+{
+    Solution s;
+    vector<vector<int>> vec = {{1,3},{0,2},{1,3},{0,2}};
+    printf("%d\n", s.isBipartite(vec));
+    return 0;
+}