切完了我的第一颗线段树

题目是洛谷的P3372，可以去看一下，传送门

算是常规模板了，先声明一下，我是数组爱好者，不喜欢用struct。代码在下面。

#include <bits/stdc++.h>
using namespace std;
#define MAXN 1000005
typedef long long ll;
ll n, m, a[MAXN], ans[MAXN << 2], tag[MAXN << 2], x, y, k, oper;
inline ll ls(ll p) {
    return p << 1;
}
inline ll rs(ll p) {
    return p << 1 | 1;
}
inline void push_up(ll p) { //do add
    ans[p] = ans[ls(p)] + ans[rs(p)];
}
void build(ll p, ll l, ll r) {
    tag[p] = 0;
    if (l == r) {
        ans[p] = a[l];
        return;
    }
    ll mid = l + r >> 1;
    build(ls(p), l, mid);
    build(rs(p), mid + 1, r);
    push_up(p);
}
inline void f(ll p, ll l, ll r, ll k) { //only modify ancestor
    tag[p] += k;
    ans[p] += k * (r - l + 1);
}
inline void push_down(ll p, ll l, ll r) {
    ll mid = (l + r) >> 1;
    f(ls(p), l, mid, tag[p]);
    f(rs(p), mid + 1, r, tag[p]);
    tag[p] = 0;
}
inline void update(ll dl, ll dr, ll l, ll r, ll p, ll k) {
    if (dl <= l && r <= dr) {
        ans[p] += k * (r - l + 1);
        tag[p] += k;
        return;
    }
    push_down(p, l, r);
    ll mid = l + r >> 1;
    if (dl <= mid)update(dl, dr, l, mid, ls(p), k);
    if (mid < dr)update(dl, dr, mid + 1, r, rs(p), k);
    push_up(p);
}
ll query(ll qx, ll qy, ll l, ll r, ll p) {
    ll res = 0;
    if (qx <= l && r <= qy)return ans[p];
    ll mid = l + r >> 1;
    push_down(p, l, r);
    if (qx <= mid)res += query(qx, qy, l, mid, ls(p));
    if (qy > mid)res += query(qx, qy, mid + 1, r, rs(p));
    return res;
}
int main() {
    scanf("%lld%lld", &n, &m);
    for (int i = 1; i <= n; i++)scanf("%lld", &a[i]);
    build(1, 1, n);
    while (m--) {
        scanf("%lld", &oper);
        if (oper == 1) {
            scanf("%lld%lld%lld", &x, &y, &k);
            update(x, y, 1, n, 1, k);
        }
        else {
            scanf("%lld%lld", &x, &y);
            printf("%lld\n", query(x, y, 1, n, 1));
        }
    }
    return 0;
}

标签：dl,线段,mid,tag,MAXN,void,第一颗,切完,ll
来源： https://www.cnblogs.com/creation-hy/p/my_first_segment_tree.html