題意:給出一個矩陣,每次詢問一個子矩陣中的最大元素,以及最大元素是不是和子矩陣的某個角相等.

二維RMQ的板子~

#include <cstdio>
#include <iostream>
#include <cstring>
#include <queue>
#include <cmath>
#include <algorithm>
#define Clear(x,y) memset (x,y,sizeof(x))
#define FOR(a,b,c) for (int a = b; a <= c; a++)
 

#define REP(a,b,c) for (int a = b; a >= c; a--)
#define fi first
#define se second
#define pii pair<int, int>
#define pli pair<long long, int>
#define pb push_back
#define mod 1000000007
using namespace std;
#define maxn 305

int n, m;
int val[maxn][maxn];
int dp[maxn][maxn][9][9];
void rmq_init ()
{
    for
 
(int row = 1; row <= n; row++)
        for(int col = 1; col <=m; col++)
            dp[row][col][0][0] = val[row][col];
    int mx = log(double(n)) / log(2.0);
    int my = log(double(m)) / log(2.0);
    for(int i=0; i<= mx; i++)
    {
        for(int j = 0; j<=my; j++)
        {
            if(i == 0
 
 && j ==0) continue;
            for(int row = 1; row+(1<<i)-1 <= n; row++)
            {
                for(int col = 1; col+(1<<j)-1 <= m; col++)
                {
                    if(i == 0)//y軸二分
                        dp[row][col][i][j]=max(dp[row][col][i][j-1],dp[row][col+(1<<(j-1))][i][j-1]);
                    else//x軸二分
                        dp[row][col][i][j]=max(dp[row][col][i-1][j],dp[row+(1<<(i-1))][col][i-1][j]);
                }
            }
        }
    }
}
int rmq (int x1,int x2,int y1,int y2)
{
    int kx = log(double(x2-x1+1)) / log(2.0);
    int ky = log(double(y2-y1+1)) / log(2.0);
    int m1 = dp[x1][y1][kx][ky];
    int m2 = dp[x2-(1<<kx)+1][y1][kx][ky];
    int m3 = dp[x1][y2-(1<<ky)+1][kx][ky];
    int m4 = dp[x2-(1<<kx)+1][y2-(1<<ky)+1][kx][ky];
    return max( max(m1,m2) , max(m3,m4));
}

int main () {
    //freopen ("more.in", "r", stdin);
    //freopen ("out", "w", stdout);
    while (scanf ("%d%d", &n, &m) == 2) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                scanf ("%d", &val[i][j]);
            }
        }
        rmq_init ();
        int q; scanf ("%d", &q);
        while (q--) {
            int x, y, xx, yy; scanf ("%d%d%d%d", &x, &y, &xx, &yy);
            int ans = rmq (x, xx, y, yy);
            printf ("%d", ans);
            if (ans == val[x][y] || ans == val[xx][y] || ans == val[x][yy] || ans == val[xx][yy])
                printf (" yes\n");
            else
                printf (" no\n");
        }
    }
    return 0;
}