HDU 4819 Mosaic 【二维线段树】

题目大意:给你一个ｎ＊ｎ的矩阵，每次找到一个点(x,y)周围ｌ＊ｌ的子矩阵中的最大值ａ和最小值ｂ，将(x,y)更新为(a+b)/2

思路:裸的二维线段树

#include<iostream>
#include<cstdio>
#include <math.h>
#include<algorithm>
#include<string.h>
#include<queue>
#define MOD 10000007
#define maxn 3500
#define LL long long
using namespace std;
int tree_max[maxn][maxn],tree_min[maxn][maxn],ans_min,ans_max,n;
int a[maxn][maxn];
void build_y(int xx,int node,int l,int r,int x,int type)
{
        if(l+1==r){
                if(type)tree_max[xx][node]=tree_min[xx][node]=a[x][l];
                else
                {
                        tree_max[xx][node]=max(tree_max[xx*2][node],tree_max[xx*2+1][node]);
                        tree_min[xx][node]=min(tree_min[xx*2][node],tree_min[xx*2+1][node]);
                }
                return ;
        }
        int mid=(l+r)>>1;
        build_y(xx,node*2,l,mid,x,type);
        build_y(xx,node*2+1,mid,r,x,type);
        tree_max[xx][node]=max(tree_max[xx][node*2],tree_max[xx][node*2+1]);
        tree_min[xx][node]=min(tree_min[xx][node*2],tree_min[xx][node*2+1]);
}
void build_x(int node,int l,int r)
{
        if(l+1==r)
        {
                build_y(node,1,1,n+1,l,1);
                return ;
        }
        int mid=(l+r)>>1;
        build_x(node*2,l,mid);
        build_x(node*2+1,mid,r);
        build_y(node,1,1,n+1,l,0);
}
void query_y(int xx,int node,int l,int r,int ql,int qr)
{
        if(ql<=l&&r<=qr)
        {
                ans_max=max(ans_max,tree_max[xx][node]);
                ans_min=min(ans_min,tree_min[xx][node]);
                return;
        }
        int mid=(l+r)>>1;
        if(ql<mid)query_y(xx,node*2,l,mid,ql,qr);
        if(qr>mid)query_y(xx,node*2+1,mid,r,ql,qr);
}
void query_x(int node,int l,int r,int ql,int qr,int y1,int y2)
{
        if(ql<=l && r<=qr)
        {
                query_y(node,1,1,1+n,y1,y2);return ;
        }
        int mid=(l+r)>>1;
        if(ql<mid)query_x(node*2,l,mid,ql,qr,y1,y2);
        if(qr>mid)query_x(node*2+1,mid,r,ql,qr,y1,y2);
}
void update_y(int xx,int node,int l,int r,int pos,int num,int type){
        if(l+1==r){
                if(type)tree_max[xx][node]=tree_min[xx][node]=num;
                else{
                        tree_max[xx][node]=max(tree_max[xx*2][node],tree_max[xx*2+1][node]);
                        tree_min[xx][node]=min(tree_min[xx*2][node],tree_min[xx*2+1][node]);
                }
                return ;
        }
        int mid=(l+r)>>1;
        if(pos<mid)update_y(xx,node*2,l,mid,pos,num,type);else
        update_y(xx,node*2+1,mid,r,pos,num,type);
        tree_max[xx][node]=max(tree_max[xx][node*2],tree_max[xx][node*2+1]);
        tree_min[xx][node]=min(tree_min[xx][node*2],tree_min[xx][node*2+1]);
}
void update_x(int node,int l,int r,int x,int y,int num)
{
        if(l+1==r)
        {
                update_y(node,1,1,n+1,y,num,1);
                return ;
        }
        int mid=(l+r)>>1;
        if(x<mid)update_x(node*2,l,mid,x,y,num);
        else update_x(node*2+1,mid,r,x,y,num);
        update_y(node,1,1,n+1,y,num,0);
}
int main()
{
        int t,cas=0;
        scanf("%d",&t);
        while(t--)
        {
                memset(tree_max,0,sizeof(tree_max));
                memset(tree_min,0,sizeof(tree_min));
                printf("Case #%d:\n",++cas);
                int q,x,y,l;
                scanf("%d",&n);
                for(int i=1;i<=n;i++)
                        for(int j=1;j<=n;j++)scanf("%d",&a[i][j]);
                build_x(1,1,n+1);
                scanf("%d",&q);
                while(q--)
                {
                        scanf("%d%d%d",&x,&y,&l);l=(l-1)>>1;
                        ans_max=0;ans_min=0x3f3f3f3f;
                        query_x(1,1,n+1,max(x-l,1),min(x+l+1,n+1),max(y-l,1),min(y+l+1,n+1));
                        update_x(1,1,n+1,x,y,(ans_max+ans_min)>>1);
                        printf("%d\n",(ans_max+ans_min)>>1);
                }
        }
        return 0;
}