可以将图的顶点划分为两个独立的集合,以使该图中的每个边要么从第一个集合开始并在第二个集合中结束,要么从第二个集合开始,连接到第一组,换句话说,我们可以说在同一组中找不到任何边缘。
通过使用顶点着色可以检查二部图。当一个顶点在同一集合中时,它具有相同的颜色,对于另一个集合,颜色将发生变化。
Input: The adjacency matrix. 0 1 1 1 0 0 1 0 0 1 1 0 1 0 0 1 0 1 1 1 1 0 1 1 0 1 0 1 0 1 0 0 1 1 1 0 Output: 该图是二分图。
isBipartite(source)
输入-源顶点。
Outpu牛逼:当图是二分真。
Begin define an empty queue qu, and a color list coloArray initially any node is not colored with any color color the source vertex as color red add source in the qu when qu is not empty, do remove item from the qu and take in u if there is any self-loop, then return false for all vertices v, which is connected with u, do if v has no color, then if colorArray[u] = red, then colorArray[v] := blue else if colorArray[u] = blue, then colorArray[v] := red add v into the queue if colorArray[v] = colorArray[u], then return false done done return true End
#include<iostream> #include<string> #include<queue> #define NODE 6 using namespace std; /*int graph[NODE][NODE] = { {0, 1, 1, 1, 0, 0}, {1, 0, 0, 1, 1, 0}, {1, 0, 0, 1, 0, 1}, {1, 1, 1, 0, 1, 1}, {0, 1, 0, 1, 0, 1}, {0, 0, 1, 1, 1, 0} }; */ int graph[NODE][NODE] = { {0, 1, 0, 0, 0, 1}, {1, 0, 1, 0, 0, 0}, {0, 1, 0, 1, 0, 0}, {0, 0, 1, 0, 1, 0}, {0, 0, 0, 1, 0, 1}, {1, 0, 0, 0, 1, 0} }; bool isBipartite(int source) { queue<int> qu; string colorArray[NODE]; for(int i = 0; i< NODE; i++) colorArray[i] = "No Color"; //initially no color is set for all vertices colorArray[source] = "Red"; //assign red with the source vertex qu.push(source); //add source into the queue. while(!qu.empty()) { int u = qu.front(); qu.pop(); if(graph[u][u] == 1) //there is a self loop return false; for(int v = 0; v < NODE; v++) { if(graph[u][v] != 0 && colorArray[v] == "No Color") { if(colorArray[u] == "Red") //assign adjacent list with alternate color colorArray[v] = "Blue"; else if(colorArray[u] == "Blue") colorArray[v] = "Red"; qu.push(v); //new adjacent node added to queue } else if(graph[u][v] != 0 && colorArray[v] == colorArray[u]) { return false; //when u and adjacent are of same color. } } } return true; } int main() { bool check; check = isBipartite(0); if(check) cout << "该图是二分图。" << endl; else cout << "该图不是二分图。" << endl; }
输出结果
该图是二分图。