POJ 1195 Mobile phones【 二维树状数组 】

题意：基础的二维数组，注意 0 + lowbit(0)会陷入无限循环-----

之前做一道一维的一直tle,就是因为这个--------------------------

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include <cmath>
 #include<stack>
 #include<vector>
 #include<map>
 #include<set>
 #include<queue>
 #include<algorithm>
 using namespace std;

 typedef long long LL;
 const int INF = (<<)-;
 const int mod=;
 const int maxn=;

 int c[][];
 int n;

 int lowbit(int x){ return x & (-x);}

 int sum(int x,int y){
     int ret = ,y1;
     while(x > ){
         y1 = y;
         while( y1 > ){
             ret += c[x][y1];y1 -= lowbit(y1);
         }
         x-=lowbit(x);
     }
     return ret;
 }

 void add(int x,int y,int d){
     int y1;
     while(x <= n){
         y1 = y;
         while(y1 <= n){
             c[x][y1] += d; y1 += lowbit(y1);
         }
         x += lowbit(x);
     }
 }

 int main(){
     int cmd;
     while(scanf("%d %d",&cmd,&n) != EOF){
         memset(c,,sizeof(c));
         while(scanf("%d",&cmd) != EOF && cmd != ){
             if(cmd == ){
                 int x,y,d;
                 scanf("%d %d %d",&x,&y,&d);x++;y++;
                 add(x,y,d);
             }
             else{
                 int x,y,xx,yy;
                 int ret = ;
                 scanf("%d %d %d %d",&x,&y,&xx,&yy);
                 x++;y++;xx++;yy++;
                 ret = sum(xx,yy) - sum(x-,yy) - sum(xx,y-) + sum(x-,y-);
                 printf("%d\n",ret);
             }
         }
     }
     return ;
 }

话说好几天没有写代码了的说啊----

加油↖(^ω^)↗

goooooooooooooooooo----