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;

}