hdu 1166敌兵布阵(线段树入门题）

Posted 2020-12-25 zengguoqiang

》》点击进入原题测试《《

思路：这两天在学线段树，这个题直接手敲一下线段树就行了，都没有用上懒人标记。入门题

cin,cout会超时，记得加std::ios::sync_with_stdio(false);

#include<string>
#include<iostream>

#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1

using namespace std;


const int maxn = 5e4 + 5;

int add[maxn << 2];
int tree[maxn << 2];

void PushDown(int rt)
{
    if (add[rt]){
        add[rt << 1] += add[rt];
        add[rt << 1 | 1] += add[rt];
        tree[rt << 1] += add[rt];
        tree[rt << 1 | 1] += add[rt];
        add[rt] = 0;
    }
}
void build(int l, int r, int rt)
{
    if (l == r){
        cin >> tree[rt];
        return;
    }
    int m = (l + r) >> 1;
    build(lson);
    build(rson);
    tree[rt] = tree[rt << 1] + tree[rt << 1 | 1];
}
void update(int x, int ans, int l, int r, int rt)
{
    if (l == r){
        tree[rt] += ans;
        return;
    }
    int m = (l + r) >> 1;
    if (x <= m)update(x, ans, lson);
    else update(x, ans, rson);
    tree[rt] = tree[rt << 1] + tree[rt << 1 | 1];
}
int query(int L, int R, int l, int r, int rt)
{
    if (L <= l&&r <= R){
        return tree[rt];
    }
    int m = (l + r) >> 1, ans = 0;
    if (L <= m)ans += query(L, R, lson);
    if (R > m)ans += query(L, R, rson);
    return ans;
}
int main()
{
    std::ios::sync_with_stdio(false);
    int t, ca = 1;
    cin >> t;
    while (t--){
        
        int n; cin >> n;
        build(1, n, 1);
        string flag; int i, j;
        cout << "Case " << ca++ << ":" << endl;
        while (cin >> flag, flag != "End"){
            cin >> i >> j;
            if (flag == "Add"){
                update(i, j, 1, n, 1);
            }
            else if (flag == "Sub"){
                update(i, -1 * j, 1, n, 1);
            }
            else if (flag == "Query"){
                cout << query(i, j, 1, n, 1) << endl;
            }
            
        }
        
    }
    return 0;
}