hdu 1166 敌兵布阵 树状数组 模板题

这题是树状数组入门的一模板题,非常基础,被小白成为"赤裸裸"的入门题,哈哈,一个plus,一个sum全部搞定

#include<stdio.h>
#include<string.h>
#define lowbit( x ) ( x )&( -x )
int tree[50024],num,n;
void plus( int num,int x )
{
     while( x <= n )
     {
            tree[x] += num;
            x += lowbit( x );
            }
 }
int sum( int x )
{
    int sum = 0;
    while( x )
    {
           sum += tree[x];
           x -= lowbit( x );
           }
    return sum;
}
int main( )
{
    int t;
    char str[100];
    scanf( "%d",&t );
    int k = t;
    while( k-- )
    {
           memset( tree,0,sizeof( tree ) );
           scanf( "%d",&n );
           for( int i = 1; i <= n; ++i )
           {
                scanf( "%d",&num );
                plus( num,i ); //第i个增加了NUM人
            }
            int r = 1; 
            while( scanf( "%s",str ),str[0] != 'E' )
            {
                   int a,b;
                   scanf( "%d%d",&a,&b );
                   switch( str[0] )
                   {
                           case 'A':
                                plus( b,a );
                                break;
                           case 'S':
                                plus( -b,a );
                                break;
                           case 'Q':
                                if( r )
                                    printf( "Case %d:\n",t - k );
                                r = 0;
                                printf("%d\n",sum( b ) - sum( a - 1 ));
                                break;
                           }
                   }
           }
    return 0;
}