[Bipartite graph] determines whether it is a bipartite graph.

The question of a game used to be a Hungarian algorithm to process the problem of the Bipartite Graph (that is, the problem is known as a bipartite graph). This is to judge the bipartite graph. Pay attention to the choice of the processing method.

Mediacy

Time Limit: 2000/1000 MS (Java/others) memory limit: 32768/32768 K (Java/Others)

Total submission (s): 103 accepted submission (s): 18

 

Problem description

In yrleep's class, there are only two kinds of relationship between the classmates which can not be passed, namely incompatible and live in harmony. so yrleep wants to put them into two parts to make both of them get along well with each other in each part. can his ideas be implemented?

 

Input

The input consists of multiple test cases. The first line input two integers n, m, n indicates the number of people

The next M lines, each line has two integers a, B, indicates a and B are incompatible.

 

Output

If his idea can come true, output yes. If not, output No.

 

 

Sample Input

 

5 3

1 2

3 4

4 5

 

Sample output

Yes

 

 

#include <cstdio>#include <iostream>#include <memory.h>#include <vector>using namespace std;const int maxn = 10000 + 10;vector G[maxn];int n, m;int color[maxn];bool dfs(int v, int c){    color[v] = c;    for(int i=0; i< G[v].size(); i++) {        //如果相邻的顶点同色，则返回false        if(color[G[v][i]] == c) return false;        //如果相邻的顶点还没有被染色，则染成-c        if(color[G[v][i]] == 0 && !dfs(G[v][i], -c)) return false;    }    return true;}void solve(){    for(int i=0; i        if(color[i] == 0) {            if(!dfs(i,1)) {                printf("no\n");                return ;            }        }    }    printf("yes\n");}int main(){//    freopen("in.txt","r",stdin);    int i, x, y;    while(~scanf("%d%d",&n,&m)) {        memset(color, 0, sizeof (color) );        for(i=1; i<=n; ++i) G[i].clear();        for(i=1; i<=m; ++i) {            scanf("%d%d",&x,&y);            G[x].push_back(y);            G[y].push_back(x);        }        solve();    }    return 0;}

[Bipartite graph] determines whether it is a bipartite graph.