(树套树,二维树状数组,二维线段树)
Given an N*N matrix A, whose elements are either 0 or 1. A[i, j] means the number in the i-th row and j-th column. Initially we have A[i, j] = 0 (1 <= i, j <= N).
We can change the matrix in the following way. Given a rectangle whose upper-left corner is (x1, y1) and lower-right corner is (x2, y2), we change all the elements in the rectangle by using "not" operation (if it is a '0' then change it into '1' otherwise change it into '0'). To maintain the information of the matrix, you are asked to write a program to receive and execute two kinds of instructions.
1. C x1 y1 x2 y2 (1 <= x1 <= x2 <= n, 1 <= y1 <= y2 <= n) changes the matrix by using the rectangle whose upper-left corner is (x1, y1) and lower-right corner is (x2, y2).
2. Q x y (1 <= x, y <= n) querys A[x, y].
Input
The first line of the input is an integer X (X <= 10) representing the number of test cases. The following X blocks each represents a test case.
The first line of each block contains two numbers N and T (2 <= N <= 1000, 1 <= T <= 50000) representing the size of the matrix and the number of the instructions. The following T lines each represents an instruction having the format "Q x y" or "C x1 y1 x2 y2", which has been described above.
Output
For each querying output one line, which has an integer representing A[x, y].
There is a blank line between every two continuous test cases.
Sample Input
1
2 10
C 2 1 2 2
Q 2 2
C 2 1 2 1
Q 1 1
C 1 1 2 1
C 1 2 1 2
C 1 1 2 2
Q 1 1
C 1 1 2 1
Q 2 1
Sample Output
1
0
0
1
题目大意:
有一个n*n的矩形平面,里面每个点初始为0,有两种操作:
1.将左上角为(x1,y1),右下角为(x2,y2)的矩形区域中的每个点,把0变成1,把1变成0
2.查询点(x,y)当前的值
Sol: 根本思想,找一个点被哪些矩形覆盖,即它在哪些矩形中。
#include<iostream> #include<cstring> #include<cstdio> #include<algorithm> #define lson l,m,rt<<1 #define rson m+1,r,rt<<1|1 #define rep(i,n) for(int i=0;i<n;++i) #define mes(s,c) memset(s,c,sizeof(s)) const int maxn=1001; using namespace std; int sum[maxn<<2][maxn<<2]; int n,m; int ans; void Subbuild(int st,int l,int r,int rt) //针对每一行,建立一个线段树 { sum[st][rt]=0; if(l==r) return ; int m=(l+r)>>1; Subbuild(st,lson); Subbuild(st,rson); } void Build(int l,int r,int rt) //建立整个线段树,一个矩形 { Subbuild(rt,1,n,1); if(l==r) return; int m=(l+r)>>1; Build(lson); Build(rson); } void Subupdate(int L,int R,int st,int l,int r,int rt) //st这个参数一直不变的,它对应x轴 //rt在调用时会发生变化,它对应y轴 { if(L<=l&&r<=R) { sum[st][rt]^=1; return ; } int m=(l+r)>>1; if(L<=m) Subupdate(L,R,st,lson); if(m<R) Subupdate(L,R,st,rson); } void Update(int x1,int y1,int x2,int y2,int l,int r,int rt) //[x1,y1]和[x2,y2]分别代表查询区域的左上角和右下解 //[l,r]代表线段上x轴的范围, rt代表对应的根结号 //在更新矩形的时候,先根据x1,x2找它们在矩形的哪个行号区域 { if(x1<=l&&r<=x2) //找到了对应的x轴区间,于是在y轴上进行修改 { Subupdate(y1,y2,rt,1,n,1); return ; } int m=(l+r)>>1; if(x1<=m) // 如果落在矩形的上半部 Update(x1,y1,x2,y2,lson); if(m<x2) Update(x1,y1,x2,y2,rson); } void Subquery(int L,int R,int st,int l,int r,int rt) //[L,R]要查询的区域,根据它们找其在y轴的左边还是右边 //st代表是属于x轴上哪个点 //[l,r]代表当前y轴上的区域 //rt代表对应[l,r]区轴上根结点编号 { ans^=sum[st][rt]; if(l==r) return; int m=(l+r)>>1; if(R<=m) //落在y轴的左边 Subquery(L,R,st,lson); else //落在y轴的右边 Subquery(L,R,st,rson); } void Query(int L,int R,int l,int r,int rt) //初始调用为Query(x,y,1,n,1); //[L,R]代表要查询的点 //[l,r]代表x轴上的区域,rt是其根 { Subquery(L,R,rt,1,n,1); //要查询的点[L,R]必然是落在当前根rt(描述所有x轴) //[1,n]代表所有列,1是其根 //也就是说当前点一定是落在整个矩形中的 //如果它是上半部的某个点,也必然是落在整个上半部中的 //就这样递归找下去,看这个点落在多少个矩形中 if(l==r) return ; int m=(l+r)>>1; if(L<=m) //落在矩形的上半部 Query(L,R,lson); else //落在矩形的下半部 Query(L,R,rson); } int main() { int T; cin>>T; while(T--){ scanf("%d%d",&n,&m); Build(1,n,1); char op[10]; int x1,y1,x2,y2,x,y; while(m--){ scanf("%s",op); if(op[0]=='C') //修改操作 { scanf("%d%d%d%d",&x1,&y1,&x2,&y2); Update(x1,y1,x2,y2,1,n,1); } else { ans=0; scanf("%d%d",&x,&y); Query(x,y,1,n,1); printf("%d ",ans); } } if(T) puts(" "); } return 0; }
//注意这题是矩形修改,然后单点询问,所以要看这个点被哪些矩形包括了. #include <stdio.h> #include <string.h> #define MAXN 1005 #define mem(a) memset(a, 0, sizeof(a)) bool tree[MAXN<<2][MAXN<<2]; int X, N, T; int num, X1, X2, Y1, Y2; char ch[10]; void updatey(int yl,int yr,int xp,int yp) { if(Y1<=yl && yr<=Y2) { tree[xp][yp]=!tree[xp][yp]; return; } int mid=(yl+yr)>>1; if(Y1<=mid) updatey(yl,mid,xp,yp<<1); if(Y2>mid ) updatey(mid+1,yr,xp,yp<<1|1); } void updatex(int xl,int xr,int xp) { if(X1<=xl && xr<=X2)//目前所在区间在所要更新区间内部 { updatey(1,N,xp,1); return; } int mid=(xl+xr)>>1; if(X1<=mid) updatex(xl,mid,xp<<1); if(X2>mid) updatex(mid+1,xr,xp<<1|1); } void queryy(int yl,int yr,int xp,int yp) { num+=tree[xp][yp];//xp代表xp轴即外面那棵树,yp代表内层那棵树 if(yl==yr) return; int mid=(yl+yr)>>1; if(Y1<=mid) queryy(yl,mid,xp,yp<<1); else queryy(mid+1,yr,xp,yp<<1|1); } void queryx(int xl,int xr,int xp) { queryy(1,N,xp,1); //对于xp这棵x轴上的线段线段树,查询y这个线段树上的第1个点,其管辖范围是1,N if(xl==xr) return; int mid=(xl+xr)>>1; if(X1<=mid) //看目标点落在整个矩形的上半部分还是下半部分 queryx(xl,mid,xp<<1); else queryx(mid+1,xr,xp<<1|1); } int main() { while(~scanf("%d", &X)) while(X--) { mem(tree); scanf("%d %d%*c", &N,&T); for(int i=0;i<T;i++) { scanf("%s%d%d",ch,&X1,&Y1); if(ch[0]=='Q') //统计(x1,y1)这个点被改了多少次, //由于我们在修改时矩形内所有点变换,所以要看哪些矩形是包含当前这个点的 { num=0; queryx(1,N,1); //1和N代表是x轴上,1代表外层线段树上第一个点,它管辖所有的点 printf("%d ",num%2);} else { scanf("%d%d",&X2,&Y2); //修改操作[X1,Y1]是左上角,[X2,Y2]是右下角 updatex(1,N,1); } } if(X) printf(" "); } return 0; }