Codeforces 611C New Year and Domino DP+容斥

"#"代表不能放骨牌的地方,"."是可以放 500*500的矩阵,q次询问

开两个dp数组,a,b,a统计横着放的方案数,b表示竖着放,然后询问时O(1)的,容斥一下, 复杂度O(n^2+q)

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cmath>
#include<cstdlib>
#include<vector>
#include<queue>
using namespace std;
typedef long long LL;
const int maxn=505;
int a[maxn][maxn];
int b[maxn][maxn];
char s[maxn][maxn];
int main()
{
    int n,m;

    while(~scanf("%d%d",&n,&m))
    {
        for(int i=1; i<=n; ++i)
            scanf("%s",s[i]+1);
        memset(a,0,sizeof(a));
        memset(b,0,sizeof(b));
        for(int i=1; i<=n; ++i)
        {
            for(int j=1; j<=m; ++j)
            {
                int k=0;
                if(s[i][j]=='.'&&s[i][j-1]=='.')k=1;
                a[i][j]+=a[i][j-1]+a[i-1][j]-a[i-1][j-1]+k;
                k=0;
                if(s[i-1][j]=='.'&&s[i][j]=='.')k=1;
                b[i][j]+=b[i-1][j]+b[i][j-1]-b[i-1][j-1]+k;
            }
        }
        int q;
        scanf("%d",&q);
        while(q--)
        {
            int x,y,l,r;
            scanf("%d%d%d%d",&x,&y,&l,&r);
            int t1=a[l][r]-a[l][y]-a[x-1][r]+a[x-1][y];
            int t2=b[l][r]-b[l][y-1]-b[x][r]+b[x][y-1];
            printf("%d
",t1+t2);
        }
    }
    return 0;
}
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原文地址:https://www.cnblogs.com/shuguangzw/p/5092607.html