Queen K——Luo Gu

The topic link
https://www.luogu.com.cn/problem/P2105
idea
Violent enumeration + oxygen optimization (not optimized for TLE), has nothing to do with dfs.
c++ code

#include<iostream>
#include<stdio.h>
#include<bits/stdc++.h>
#define N 20020
using namespace std;
int n,m,K;
int sum;
int a[N],b[N],c[N*2],d[N*2];
int main()
{
    
    
    scanf("%d%d%d",&n,&m,&K);
    for(int i=1;i<=K;i++)
    {
    
    
        int x,y;
        scanf("%d%d",&x,&y);
        a[x]=1;
        b[y]=1;
        c[x+y]=1;
        d[x-y+N]=1;
    }
    for(int i=1;i<=n;i++)
    {
    
    
        if(a[i]) continue;
            for(int j=1;j<=m;j++)
            {
    
    
                if(!a[i]&&!b[j]&&!c[i+j]&&!d[i-j+N])
                {
    
    
                    sum++;
                }
            }
    }
    printf("%d\n",sum);
    return 0;
}