https://www.luogu.com.cn/problem/AT_abc128_d
#include <bits/stdc++.h>
using namespace std;
int n, m, g[1005][1005], fl, vis[1005], col[1005];
void dfs(int u) {
// cout<<"uuu "<<u<<" "<<col[u]<<endl;
for (int v = 1; v <= n; v++) {
if (v == u)
continue;
// cout<<"vvv "<<v<<" "<<col[v]<<endl;
if (g[u][v]) {
if (vis[v]) {
if (col[v] != col[u]) {
cout << "NE" << endl;
fl = 0;
exit(0);
}
} else {
col[v] = col[u];
vis[v] = 1;
dfs(v);
}
} else {
if (vis[v]) {
if (col[v] == col[u]) {
cout << "NE" << endl;
fl = 0;
exit(0);
}
} else {
col[v] = col[u] ^ 1;
vis[v] = 1;
dfs(v);
}
}
}
// cout<<"pppp"<<endl;
// cout<<endl;
}
int main() {
scanf("%d%d", &n, &m);
for (int i = 1; i <= m; i++) {
int x, y;
scanf("%d%d", &x, &y);
g[x][y] = g[y][x] = 1;
}
fl = 1;
vis[1] = col[1] = 1;
dfs(1);
if (fl == 1)
cout << "DA" << endl;
return 0;
}
二分图染色的两种方法：染色法，并查集补集法
