这是按照自己理解写的一个测试代码。。。
简单易懂
#include<stdio.h> #include<string.h> #include<stdlib.h> const int maxn = 10005; int a[ maxn ],c[ maxn ]; int lowbit( int i ){ return i&(-i); } int sum( int i ){ int s=0; while( i>0 ){ s+=c[ i ]; i-=lowbit( i ); } return s; } void update( int i,int new_val,int pre_val ){ while( i<maxn ){ c[ i ]-=pre_val; c[ i ]+=new_val; i+=lowbit( i ); } } void test( int n ){ printf("\n\n"); for( int i=1;i<=n;i++ ) printf("%d ",a[ i ]); printf("\n\n"); } int main(){ int n; while( scanf("%d",&n)==1 ){ memset( a,0,sizeof( a ) ); memset( c,0,sizeof( c ) ); for( int i=1;i<=n;i++ ){ scanf("%d",&a[ i ]); update( i,a[ i ],0 ); } int m; scanf("%d",&m); while( m-- ){ int op; scanf("%d",&op); if( op==1 ){ int pos,new_val; scanf("%d%d",&pos,&new_val); test( n ); update( pos,new_val,a[ pos ] ); a[ pos ]=new_val; test( n );//输出1 到 n }//change a[ pos ] to new_val else if( op==2 ){ int from,to; scanf("%d%d",&from,&to); if( from>1 ) printf("from %d to %d:%d\n",from,to,sum( to )-sum( from-1 ) ); else printf("from %d to %d:%d\n",from,to,sum( to ) ); }//询问从from到to的总和 } } return 0; }