poj 2019 Cornfields (二维rmq)

  1/* ***********************************************
  2Author :111qqz
  3Created Time :2016年05月16日 星期一 18时31分23秒
  4File Name :code/poj/2019.cpp
  5************************************************ */
  6
  7#include <cstdio>
  8#include <cstring>
  9#include <iostream>
 10#include <algorithm>
 11#include <vector>
 12#include <queue>
 13#include <set>
 14#include <map>
 15#include <string>
 16#include <cmath>
 17#include <cstdlib>
 18#include <ctime>
 19#define fst first
 20#define sec second
 21#define lson l,m,rt<<1
 22#define rson m+1,r,rt<<1|1
 23#define ms(a,x) memset(a,x,sizeof(a))
 24typedef long long LL;
 25#define pi pair < int ,int >
 26#define MP make_pair
 27
 28using namespace std;
 29const double eps = 1E-8;
 30const int dx4[4]={1,0,0,-1};
 31const int dy4[4]={0,-1,1,0};
 32const int inf = 0x3f3f3f3f;
 33const int N=251;
 34int a[N][N];
 35int dp[N][N][8][8];
 36int dp2[N][N][8][8];
 37int n,b,q;
 38
 39void init_rmq()
 40{
 41    for ( int i = 1 ;i  <= n ; i++)
 42	for ( int j = 1 ; j <= n ; j++)
 43	    dp[i][j][0][0] = dp2[i][j][0][0] = a[i][j];
 44
 45
 46    for ( int i = 0 ; (1<<i)<= n ; i++)
 47	for ( int  j = 0 ;  (1<<j) <= n ; j++)
 48	    if (i==0 && j==0) continue;
 49	    else for ( int p = 1 ; p + (1<<i)-1 <= n ; p++)
 50		    for ( int q = 1 ; q + (1<<j)-1 <= n ; q++)
 51			if (i==0)
 52			{
 53			    dp[p][q][i][j] = max(dp[p][q][i][j-1],dp[p][q+(1<<(j-1))][i][j-1]);
 54			    dp2[p][q][i][j] = min(dp2[p][q][i][j-1],dp2[p][q+(1<<(j-1))][i][j-1]);
 55			}
 56			else
 57			{
 58			    dp[p][q][i][j] = max(dp[p][q][i-1][j],dp[p+(1<<(i-1))][q][i-1][j]);
 59			    dp2[p][q][i][j] = min(dp2[p][q][i-1][j],dp2[p+(1<<(i-1))][q][i-1][j]);
 60			}
 61}
 62
 63
 64int _rmq(int x1,int y1,int x2,int y2)
 65{
 66    int k1 = 0 ;
 67    int k2 = 0 ;
 68    while (1<<(k1+1)<=x2-x1+1) k1++;
 69    while (1<<(k2+1)<=y2-y1+1) k2++;
 70
 71    int tmp1 = dp[x1][y1][k1][k2];
 72    int tmp2 = dp[x2-(1<<k1)+1][y1][k1][k2];
 73    int tmp3 = dp[x1][y2-(1<<k2)+1][k1][k2];
 74    int tmp4 = dp[x2-(1<<k1)+1][y2-(1<<k2)+1][k1][k2];
 75
 76    int mx =  max(max(tmp1,tmp2),max(tmp3,tmp4));
 77
 78    tmp1 = dp2[x1][y1][k1][k2];
 79    tmp2 = dp2[x2-(1<<k1)+1][y1][k1][k2];
 80    tmp3 = dp2[x1][y2-(1<<k2)+1][k1][k2];
 81    tmp4 = dp2[x2-(1<<k1)+1][y2-(1<<k2)+1][k1][k2];
 82
 83    int mn = min(min(tmp1,tmp2),min(tmp3,tmp4));
 84
 85   // cout<<"mx:"<<mx<<" mn:"<<mn<<endl;
 86
 87    return mx - mn;
 88}
 89
 90
 91int main()
 92{
 93	#ifndef  ONLINE_JUDGE 
 94	freopen("code/in.txt","r",stdin);
 95  #endif
 96	scanf("%d %d %d",&n,&b,&q);
 97	for ( int i = 1 ; i <= n ; i++)
 98	    for ( int j = 1 ; j <= n ; j++) scanf("%d",&a[i][j]);
 99	init_rmq();
100
101	while (q--)
102	{
103	    int x1,y1;
104	    scanf("%d %d",&x1,&y1);
105	    printf("%d\n",_rmq(x1,y1,x1+b-1,y1+b-1));
106	}
107
108
109
110  #ifndef ONLINE_JUDGE  
111  fclose(stdin);
112  #endif
113    return 0;
114}