HDU 4819 Mosaic （二维线段树&区间最值）题解

思路：

二维线段树模板题，马克一下，以后当模板用

代码：

#include<cstdio>
#include<cmath>
#include<cstring>
#include<iostream>
#include<algorithm>
#define ll long long
using namespace std;
const int N = 1024+5;
int MAX[N<<2][N<<2],MIN[N<<2][N<<2],n,minv,maxv;
void push_upx(int deep,int rt){
    MAX[deep][rt] = max(MAX[deep<<1][rt],MAX[deep<<1|1][rt]);
    MIN[deep][rt] = min(MIN[deep<<1][rt],MIN[deep<<1|1][rt]);
}
void push_upy(int deep,int rt){
    MAX[deep][rt] = max(MAX[deep][rt<<1],MAX[deep][rt<<1|1]);
    MIN[deep][rt] = min(MIN[deep][rt<<1],MIN[deep][rt<<1|1]);
}
void buildy(int ly,int ry,int deep,int rt,int flag){
    //y轴范围ly,ry;deep,rt;标记flag
    if(ly == ry){
        if(flag){
            int tmp;
            scanf("%d",&tmp);
            MAX[deep][rt] = MIN[deep][rt] = tmp;
        }
        else push_upx(deep,rt);
        return;
    }
    int m = (ly + ry) >> 1;
    buildy(ly,m,deep,rt << 1,flag);
    buildy(m+1,ry,deep,rt << 1 | 1,flag);
    push_upy(deep,rt);
}
void buildx(int lx,int rx,int deep){
    //建树x轴范围lx,rx;deep
    if(lx == rx){
        buildy(1,n,deep,1,1);
        return;
    }
    int m = (lx + rx) >> 1;
    buildx(lx,m,deep << 1);
    buildx(m+1,rx,deep << 1 | 1);
    buildy(1,n,deep,1,0);
}
void updatey(int Y,int val,int ly,int ry,int deep,int rt,int flag){
    //单点更新y坐标;更新值val;当前操作y的范围ly,ry;deep,rt;标记flag
    if(ly == ry){
        if(flag) MAX[deep][rt] = MIN[deep][rt] = val;
        else push_upx(deep,rt);
        return;
    }
    int m = (ly + ry) >> 1;
    if(Y <= m) updatey(Y,val,ly,m,deep,rt << 1,flag);
    else updatey(Y,val,m + 1,ry,deep,rt << 1 | 1,flag);
    push_upy(deep,rt);
}
void updatex(int X,int Y,int val,int lx,int rx,int deep){
    //单点更新范围x,y;更新值val;当前操作x的范围lx,rx;deep
    if(lx == rx){
        updatey(Y,val,1,n,deep,1,1);
        return;
    }
    int m = (lx + rx) >> 1;
    if(X <= m) updatex(X,Y,val,lx,m,deep << 1);
    else updatex(X,Y,val,m + 1,rx,deep << 1 | 1);
    updatey(Y,val,1,n,deep,1,0);
}
void queryy(int Yl,int Yr,int ly,int ry,int deep,int rt){
    //询问区间y轴范围y1,y2;当前操作y的范围ly,ry;deep,rt
    if(Yl <= ly && ry <= Yr){
        minv = min(MIN[deep][rt],minv);
        maxv = max(MAX[deep][rt],maxv);
        return;
    }
    int m = (ly + ry) >> 1;
    if(Yl <= m)
        queryy(Yl,Yr,ly,m,deep,rt << 1);
    if(m < Yr)
        queryy(Yl,Yr,m + 1,ry,deep,rt << 1 | 1);
}
void queryx(int Xl,int Xr,int Yl,int Yr,int lx,int rx,int rt){
    //询问区间范围x1,x2,y1,y2;当前操作x的范围lx,rx;rt
    if(Xl <= lx && rx <= Xr){
        queryy(Yl,Yr,1,n,rt,1);
        return;
    }
    int m = (lx + rx) >> 1;
    if(Xl <= m)
        queryx(Xl,Xr,Yl,Yr,lx,m,rt << 1);
    if(m < Xr)
        queryx(Xl,Xr,Yl,Yr,m + 1,rx,rt << 1 | 1);
}
int main(){
    int T,Case = 1;
    scanf("%d",&T);
    while(T--){
        //memset(MAX,-1,sizeof(MAX));
        //memset(MIN,63,sizeof(MIN));
        scanf("%d",&n);
        buildx(1,n,1);
        int q,X,Y,r,odd,x1,x2,y1,y2;
        scanf("%d",&q);
        printf("Case #%d:
",Case++);
        while(q--){
            maxv = -1,minv = 1000000005;
            scanf("%d%d%d",&X,&Y,&odd);
            r = odd >> 1;
            x1 = max(X - r,1);    //注意一下范围
            y1 = max(Y - r,1);
            x2 = min(X + r,n);
            y2 = min(Y + r,n);
            queryx(x1,x2,y1,y2,1,n,1);
            int ans = (maxv + minv) >> 1;
            printf("%d
",ans);
            updatex(X,Y,ans,1,n,1);
        }
    }
    return 0;
}