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graph_bipartite1707_2.cpp
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50 lines (50 loc) · 1.12 KB
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#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <queue>
using namespace std;
vector<int> a[20001];
int color[20001];
bool dfs(int node, int c) {
color[node] = c;
for (int i=0; i<a[node].size(); i++) {
int next = a[node][i];
if (color[next] == 0) {
if (dfs(next, 3-c) == false) {
return false;
}
} else if (color[next] == color[node]) {
return false;
}
}
return true;
}
int main() {
int t;
scanf("%d\n",&t);
while (t--) {
int n, m;
scanf("%d %d",&n,&m);
for (int i=1; i<=n; i++) {
a[i].clear();
color[i] = 0;
}
for (int i=0; i<m; i++) {
int u,v;
scanf("%d %d",&u,&v);
a[u].push_back(v);
a[v].push_back(u);
}
bool ok = true;
for (int i=1; i<=n; i++) {
if (color[i] == 0) {
if (dfs(i, 1) == false) {
ok = false;
}
}
}
printf("%s\n",ok ? "YES" : "NO");
}
return 0;
}