Hdu1166单点更新线段树

 

 

入门线段树，单点更新。写了几遍，都是学着notonlysuccess写的。

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>

using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
int sum[444444];
void up(int rt)
{
    sum[rt] = sum[rt << 1] + sum[rt << 1 | 1];
}

void build(int l, int r, int rt)
{
    if (l == r){
        scanf("%d", &sum[rt]); return;
    }
    int mid = (l + r) >> 1;
    build(lson);
    build(rson);
    up(rt);
}

void update(int key, int add, int l, int r, int rt)
{
    if (l == r){
        sum[rt] += add; return;
    }
    int mid = (l + r) >> 1;
    if (key <= mid) update(key, add, lson);
    else update(key, add, rson);
    up(rt);
}

int ask(int L, int R, int l, int r, int rt)
{
    if (L <= l&&r <= R) return sum[rt];
    int mid = (l + r) >> 1;
    int ans = 0;
    if (L <= mid) ans += ask(L, R, lson);
    if (R>mid) ans += ask(L, R, rson);
    return ans;
}
char str[100];
int main()
{
    int Icase; int n;
    scanf("%d", &Icase);
    int tt = 0;
    while (Icase--){
        printf("Case %d:\n", ++tt);
        scanf("%d", &n);
        build(1, n, 1);
        for (;;){
            int a; int b;
            scanf("%s", str); if (str[0] == 'E') break; scanf("%d%d", &a, &b);
            if (str[0] == 'A'){
                update(a, b, 1, n, 1);
            }
            if (str[0] == 'S'){
                update(a, -b, 1, n, 1);
            }
            if (str[0] == 'Q'){
                printf("%d\n", ask(a, b, 1, n, 1));
            }
        }
    }
    return 0;
}