这道题真的,我哭死QWQ
自己想的这段代码没有过去,只过去了14个样例(共19),

#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
int n, m, e[N], ne[N], h[N], idx, color[N];
queue<int> q;
void add(int a, int b)
{
  e[idx] = b;
  ne[idx] = h[a];
  h[a] = idx++;
}
bool dfs(int x)
{
  for (int i = h[x]; i != -1; i = ne[i])
  {
    int j = e[i];
    if (!color[j])
      color[j] = 3 - color[x], q.push(j);
    else
    {
      if (color[j] == color[x])
        return false;
      else
        continue;
    }
    return true;
  }
}
  int main()
  {
    memset(h, -1, sizeof h);
    cin >> n >> m;
    while (m--)
    {
      int v, p;
      cin >> v >> p;
      add(v, p);
      add(p, v);
    }
    q.push(1);
    color[1] = 1;
    while (q.size())
    {
      auto t = q.front();
      q.pop();
      if (dfs(t))
        continue;
      else
      {
        cout << "No" << endl;
        return 0;
      }
    }
    cout << "Yes" << endl;
    return 0;
  }

然后我去学了y总的
我想了一下,这是在数据过10000+时发生的答案错误,在插入一个数要对那个数造成的影响负责(dfs()),不能仅仅赋值(color[j] = 3-c;)

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10,M = 1e6 + 10;
int n, m,color[N],ne[M],e[M],h[N],idx;
void add(int a,int b)
{
  e[idx] = b;
  ne[idx] = h[a];
  h[a] = idx++;
}
bool dfs(int u,int c)
{
  color[u] = c;
  for (int i = h[u]; ~i ; i=ne[i]) {
    int j = e[i];
    if(!color[j]) {
      if(!dfs(j,3-c)) return false;//有谁跟我一样这里一开始写的是 color[j]=3-c;QWQ
    }
    else if(color[j]==color[u])
      return false;
  }
  return true;
}
int main()
{
  memset(h, -1, sizeof h);
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int v, p;cin >> v >> p;
    add(v, p);
    add(p, v);
  }
  for (int i = 1; i <= n; i++) {
    if (!color[i]) {
      if(!dfs(i,1)) {
        cout << "No";
        return 0;
      }
    } 
  }
  cout << "Yes";
  return 0;
}