POJ 2019 Cornfields 二维线段树的初始化与最值查询

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <queue>
#include <cmath>
#include <stack>
#include <map>

#pragma comment(linker, "/STACK:1024000000");
#define EPS (1e-8)
#define LL long long
#define ULL unsigned long long
#define _LL __int64
#define _INF 0x3f3f3f3f
#define Mod 9999991
#define lowbit(x) (x&(-x))

using namespace std;

struct N
{
int Min,Max;
}st[1200][1200];

int num[310][310];

void Init_Y(int s1,int s2,int l,int r,int t,int b)
{

if(t == b)
{
if(l == r)
{
st[s1][s2].Max = num[l][t];
st[s1][s2].Min = num[l][t];
}
else
{

st[s1][s2].Max = max(st[s1<<1][s2].Max,st[s1<<1|1][s2].Max);
st[s1][s2].Min = min(st[s1<<1][s2].Min,st[s1<<1|1][s2].Min);
}
return ;
}

int mid = (t+b)>>1;

Init_Y(s1,s2<<1,l,r,t,mid);
Init_Y(s1,s2<<1|1,l,r,mid+1,b);

st[s1][s2].Max = max(st[s1][s2<<1].Max,st[s1][s2<<1|1].Max);
st[s1][s2].Min = min(st[s1][s2<<1].Min,st[s1][s2<<1|1].Min);
}

void Init_X(int s1,int s2,int l,int r,int t,int b)
{
if(l != r)
{
int mid = (l+r)>>1;

Init_X(s1<<1,s2,l,mid,t,b);
Init_X(s1<<1|1,s2,mid+1,r,t,b);
}

Init_Y(s1,s2,l,r,t,b);
}

N Query_Y(int s1,int s2,int L,int R,int T,int B,int l,int r,int t,int b)
{
if(T == t && B == b)
return st[s1][s2];

int mid = (T+B)>>1;

if(b <= mid)
return Query_Y(s1,s2<<1,L,R,T,mid,l,r,t,b);
else if(mid < t)
return Query_Y(s1,s2<<1|1,L,R,mid+1,B,l,r,t,b);
N temp,t1,t2;

t1 = Query_Y(s1,s2<<1,L,R,T,mid,l,r,t,mid);
t2 = Query_Y(s1,s2<<1|1,L,R,mid+1,B,l,r,mid+1,b);

temp.Max = max(t1.Max,t2.Max);
temp.Min = min(t1.Min,t2.Min);
return temp;
}

N Query_X(int s1,int s2,int L,int R,int T,int B,int l,int r,int t,int b)
{
if(L == l && R == r)
{
return Query_Y(s1,s2,L,R,T,B,l,r,t,b);
}

int mid = (L+R)>>1;

if(r <= mid)
return Query_X(s1<<1,s2,L,mid,T,B,l,r,t,b);
else if(mid < l)
return Query_X(s1<<1|1,s2,mid+1,R,T,B,l,r,t,b);
N temp,t1,t2;
t1 = Query_X(s1<<1,s2,L,mid,T,B,l,mid,t,b);
t2 = Query_X(s1<<1|1,s2,mid+1,R,T,B,mid+1,r,t,b);
temp.Max = max(t1.Max,t2.Max);
temp.Min = min(t1.Min,t2.Min);
return temp;
}

int main()
{
int n,m,k,b,i,j,x,y;

scanf("%d %d %d",&n,&b,&k);

for(i = 1;i <= n; ++i)
{
for(j = 1;j <= n; ++j)
{
scanf("%d",&num[i][j]);
}
}

Init_X(1,1,1,n,1,n);

while(k--)
{
scanf("%d %d",&x,&y);

N temp = Query_X(1,1,1,n,1,n,x,min(n,x+b-1),y,min(n,y+b-1));

printf("%d\n",temp.Max-temp.Min);
}

return 0;
}