线段树的基本运算

#include<cstdio>
#include<cstring>
const int maxn=100010;
#define lowbit(i) ((i)&(i))
int c[maxn];

void update(int x,int v) {
 for(int i=x;i<maxn;i+=lowbit(i)) {
  c[i]+=v;
 }
}

int getsum(int x) {
 int sum=0;
 for(int i=x;i>=;i-=lowbit(i)) {
  sum+=c[i];
 }
 return sum;
}

来源：https://www.cnblogs.com/superPG/p/12298097.html