【poj 1195】Mobile phones 二维树状数组

Mobile phones
Time Limit: 5000MS Memory Limit: 65536K
Total Submissions: 17500 Accepted: 8093

Description
Suppose that the fourth generation mobile phone base stations in the Tampere area operate as follows. The area is divided into squares. The squares form an S * S matrix with the rows and columns numbered from 0 to S-1. Each square contains a base station. The number of active mobile phones inside a square can change because a phone is moved from a square to another or a phone is switched on or off. At times, each base station reports the change in the number of active phones to the main base station along with the row and the column of the matrix.

Write a program, which receives these reports and answers queries about the current total number of active mobile phones in any rectangle-shaped area.

Input
The input is read from standard input as integers and the answers to the queries are written to standard output as integers. The input is encoded as follows. Each input comes on a separate line, and consists of one instruction integer and a number of parameter integers according to the following table.

The values will always be in range, so there is no need to check them. In particular, if A is negative, it can be assumed that it will not reduce the square value below zero. The indexing starts at 0, e.g. for a table of size 4 * 4, we have 0 <= X <= 3 and 0 <= Y <= 3.

Table size: 1 * 1 <= S * S <= 1024 * 1024
Cell value V at any time: 0 <= V <= 32767
Update amount: -32768 <= A <= 32767
No of instructions in input: 3 <= U <= 60002
Maximum number of phones in the whole table: M= 2^30

Output
Your program should not answer anything to lines with an instruction other than 2. If the instruction is 2, then your program is expected to answer the query by writing the answer as a single line containing a single integer to standard output.

Sample Input

0 4
1 1 2 3
2 0 0 2 2
1 1 1 2
1 1 2 -1
2 1 1 2 3
3

Sample Output

3
4

Source
IOI 2001

题目链接：http://poj.org/problem?id=1195

题意：给你一个矩阵（初始化为0）和一些操作，1 x y a表示在arr[x][y]加上a，2 l b r t 表示求左上角为(l,b),右下角为(r,t)的矩阵的和。3.end game

思路：二维树状数组 *裸
注意坐标从0开始
两个循环计算，get(c+1,d+1)+get(a,b)-get(c+1,b)-get(a,d+1)
相当于求面积

代码：

#include<iostream>
#include<string.h>
#include<stdio.h>
using namespace std;
#define maxn 1105
int C[maxn][maxn];
int n;

int get(int x,int y)
{
    int ret=0;
    while(x>0)
    {
        int yy=y;
        while(yy>0)
        {

            ret+=C[x][yy];
            //cout<<x<<" "<<y<<" "<<C[x][y]<<endl;
            yy-=yy&(-yy);
        }
        x-=x&(-x);
    }
    return ret;
}
void add(int x,int y,int c)
{
    while(x<=n)
    {
        int yy=y;
        while(yy<=n)
        {
            C[x][yy]+=c;
            //cout<<x<<" "<<yy<<" "<<C[x][yy]<<endl;
            yy+=yy&(-yy);
        }
        x+=x&(-x);

    }
}
int main()
{
    int p;
    int a,b,c,d;
    while(scanf("%d",&p)!=EOF)
    {
        if(p==3) return 0;
        if(!p)
        {
            scanf("%d",&n);
            memset(C,0,sizeof(C));
        }
        else if(p==1)
        {
            scanf("%d%d%d",&a,&b,&c);
            add(a+1,b+1,c);
            //printf("%d\n",get(4,4));
        }
        else if(p==2)
        {
            scanf("%d%d%d%d",&a,&b,&c,&d);
            printf("%d\n",get(c+1,d+1)+get(a,b)-get(c+1,b)-get(a,d+1));

        }
    }

}