UVA 12086 - Potentiometers(树状数组)

题目链接

树状数组裸题。

细节参见代码：

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 200000 + 5;
const int INF = 1000000000;
int n,m,x,y,a[maxn],kase = 0,bit[maxn];
ll sum(int x) {
    ll ret = 0;
    while(x > 0) {
        ret += bit[x]; x -= (x & -x);
    }
    return ret;
}
void add(int x,int d) {
    while(x <= n) {
        bit[x] += d; x += (x & -x);
    }
}
char s[10];
int main() {
    while(~scanf("%d",&n)&&n) {
        memset(bit,0,sizeof(bit));
        for(int i=1;i<=n;i++) {
            scanf("%d",&a[i]);
            add(i,a[i]);
        }
        if(kase) printf("\n");
        printf("Case %d:\n",++kase);
        while(~scanf("%s",s)&&s[0]!='E') {
            scanf("%d%d",&x,&y);
            if(s[0] == 'S') {
                add(x,y-a[x]);
                a[x] = y;
            }
            else printf("%d\n",sum(y)-sum(x-1));
        }
    }
    return 0;
}