牛客小白月赛20 E 区区区间

题目链接：

解法：用tag数组维护区间最左端的数即可

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ls(p) p << 1
#define rs(p) p << 1 | 1
const int M = 2e5 + 10;
ll ans[M << 2], tag[M << 2];
int a[M];
void push_up(int p) {
    ans[p] = ans[ls(p)] + ans[rs(p)];
}
void build(int p, int l, int r) {
    tag[p] = 0;
    if(l == r) {
        ans[p] = a[l];
        return;
    }
    int mid = l + r >> 1;
    build(ls(p), l, mid);
    build(rs(p), mid + 1, r);
    push_up(p);
}
void push_down(int p, int p_l, int p_r) {
    if(!tag[p]) return;
    int mid = p_l + p_r >> 1;
    tag[ls(p)] = tag[p];
    ans[ls(p)] = 1ll * (mid - p_l + 1ll) * (1ll * 2 * tag[ls(p)] + (ll)mid - p_l) / 2;
    tag[rs(p)] = tag[p] + mid - p_l + 1;
    ans[rs(p)] = 1ll * ((ll)p_r - mid) * (1ll * 2 * tag[rs(p)] + (ll)p_r - mid - 1) / 2;
    tag[p] = 0;
}
void add(int p, int p_l, int p_r, int l, int r, int x) {
    if(p_l >= l && p_r <= r) {
        tag[p] = p_l - l + x;
        ans[p] = 1ll * (p_r - p_l + 1ll) * (1ll * 2 * tag[p] + (ll)p_r - p_l) / 2;
        return;
    }
    push_down(p, p_l, p_r);
    int mid = p_l + p_r >> 1;
    if(l <= mid) add(ls(p), p_l, mid, l, r, x);
    if(r > mid) add(rs(p), mid + 1, p_r, l, r, x);
    push_up(p);
}
ll query(int p, int p_l, int p_r, int l, int r) {
    ll sum = 0;
    if(p_l >= l && p_r <= r) {
        return ans[p];
    }
    push_down(p, p_l, p_r);
    int mid = p_l + p_r >> 1;
    if(l <= mid) sum += query(ls(p), p_l, mid, l, r);
    if(r > mid) sum += query(rs(p), mid + 1, p_r, l, r);
    return sum;
}
int main(){
    int n, m;
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= n; i++) scanf("%d", &a[i]);
    build(1, 1, n);
    while(m--) {
        int opt, l, r, x;
        scanf("%d", &opt);
        if(opt == 1) {
            scanf("%d%d%d", &l, &r, &x);
            add(1, 1, n, l, r, x);
        }
        else {
            scanf("%d%d", &l, &r);
            printf("%lld
", query(1, 1, n, l, r));
        }
    }
    return 0;
}