zoj 2859 Matrix Searching

题目链接:http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=1859

题目大意:求矩阵中任意子矩阵中的最小值.

题目思路:二维线段树.
对于这题更新相当于是单点的,所以树套树的线段树应该会比矩形树更快.
因为不懂得树套树如何对整个区间的更新(和这题没关系),所以我写二维线段树,一般都采用矩形树.

代码:

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <math.h>
#include <time.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <string>
#include <iostream>
#include <algorithm>
using namespace std;

//#define ull unsigned __int64
//#define ll __int64
//#define ull unsigned long long
//#define ll long long
#define son1 New(p.xl,xm,p.yl,ym),(rt<<2)-2
#define son2 New(p.xl,xm,min(ym+1,p.yr),p.yr),(rt<<2)-1
#define son3 New(min(xm+1,p.xr),p.xr,p.yl,ym),rt<<2
#define son4 New(min(xm+1,p.xr),p.xr,min(ym+1,p.yr),p.yr),rt<<2|1
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define middle (l+r)>>1
#define MOD 1000000007
#define esp (1e-8)
const int INF=0x3F3F3F3F;
const double DINF=10000.00;
//const double pi=acos(-1.0);
const int N=310;
int n,m;
int mmin[(N<<2)*(N<<2)];
int mtx[N][N];
struct node{
	int xl,xr,yl,yr;
	int xmid(){return (xl+xr)>>1;}
	int ymid(){return (yl+yr)>>1;}
};
node New(int xl,int xr,int yl,int yr){
	node r;
	r.xl=xl,r.xr=xr;
	r.yl=yl,r.yr=yr;
	return r;
}

void PushUp(int rt){
	int t1=min(mmin[(rt<<2)-2],mmin[(rt<<2)-1]);
	int t2=min(mmin[rt<<2],mmin[rt<<2|1]);
	mmin[rt]=min(t1,t2);
}
void Build(node p,int rt){
	if(p.xl==p.xr && p.yl==p.yr){
		mmin[rt]=mtx[p.xl][p.yl];
		return;
	}
	int xm=p.xmid(),ym=p.ymid();
	Build(son1);Build(son2);
	Build(son3);Build(son4);
	PushUp(rt);
}

int Query(node p,int rt,node P){
	if((P.xl<=p.xl&&p.xr<=P.xr)&&(P.yl<=p.yl&&p.yr<=P.yr))
		return mmin[rt];
	int xm=p.xmid(),ym=p.ymid(),ret=INF;
	if(P.xl<=xm){
		if(P.yl<=ym) ret=min(ret,Query(son1,P));
		if(ym<P.yr) ret=min(ret,Query(son2,P));
	}
	if(xm<P.xr){
		if(P.yl<=ym) ret=min(ret,Query(son3,P));
		if(ym<P.yr) ret=min(ret,Query(son4,P));
	}
	return ret;
}

int main(){
	//freopen("1.in","r",stdin);
	//freopen("1.out","w",stdout);
	int i,j,k,r1,c1,r2,c2;
	int T,cas;scanf("%d",&T);for(cas=1;cas<=T;cas++){
		scanf("%d",&n);
		for(i=1;i<=n;i++)
			for(j=1;j<=n;j++)
				scanf("%d",&mtx[i][j]);
		Build(New(1,n,1,n),1);
		scanf("%d",&m);
		while(m--){
			scanf("%d%d%d%d",&r1,&c1,&r2,&c2);
			if(r1>r2) swap(r1,r2);
			if(c1>c2) swap(c1,c2);
			printf("%d\n",Query(New(1,n,1,n),1,New(r1,r2,c1,c2)));
		}
	}
	return 0;
}