线段树（点查询、区间查询、区间修改）模板

简单记录一下自己的代码，以后方便复习
其实有了这样子的一个模板，题目变式自己改改就可以，比如说加减变成乘除等等。

#pragma GCC optimize(3,"Ofast","inline")
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <math.h>
#include <string>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <stdlib.h>
#define maxn 1000005
//#define true false
//#define false true
const int MaxN = 0x3f3f3f3f;
const int MinN = 0xc0c0c00c;
const double pi = acos(-1);
typedef long long ll;
const int mod = 1e9 + 7;
using namespace std;
ll arr[maxn];
ll tree[maxn];
ll add[maxn];
void build_tree(ll node, ll start, ll ends) {
    if (start == ends)   tree[node] = arr[start];
    else {
        ll mid = (start + ends) / 2;
        build_tree(2 * node, start, mid);
        build_tree(2 * node + 1, mid + 1, ends);
        tree[node] = tree[2 * node] + tree[2 * node + 1];
    }
}
void update_treepoint(ll node, ll start, ll ends, ll idx, ll val) {  //单点修改
    if (start == ends) {
        arr[idx] = val;
        tree[node] = val;
    }
    else {
        ll mid = (start + ends) / 2;
        if (idx >= start && idx <= mid)   update_treepoint(2 * node, start, mid, idx, val);
        else        update_treepoint(2 * node+1, mid + 1, ends, idx, val);
        tree[node] = tree[2 * node] + tree[2 * node+1];
    }
}
void Add(ll node, ll start, ll ends, ll val) {
    add[node] += val;
    tree[node] += (ends - start + 1) * val;
    return;
}
void pushdown(ll node, ll start, ll ends, ll mid) {
    if (add[node] == 0) return;
    Add(node * 2, start, mid, add[node]);
    Add(node * 2 + 1, mid + 1, ends, add[node]);
    add[node] = 0;
}
void update_section(ll node, ll start, ll ends, ll l, ll r, ll val) {
    if (start >= l && ends <= r)  return Add(node, start, ends, val);
    ll mid = (start + ends) / 2;
    pushdown(node, start, ends, mid);
    if (l <= mid)  update_section(node * 2, start, mid, l, r, val);
    if (mid < r)   update_section(node * 2 + 1, mid + 1, ends, l, r, val);
    tree[node] = tree[node * 2] + tree[node * 2 + 1];
}
ll query_tree(ll node, ll start, ll ends, ll l, ll r) {
    if (start >= l && ends <= r)  return tree[node];
    ll mid = (start + ends) / 2, ans = 0;
    pushdown(node, start, ends, mid);
    if (l <= mid)  ans += query_tree(node * 2, start, mid, l, r);
    if (r > mid)   ans += query_tree(node * 2 + 1, mid + 1, ends, l, r);
    return ans;
}
int main()
{
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) scanf("%lld", &arr[i]);
    build_tree(1, 1, n);
    ll flag;
    while (m--) {
        scanf("%lld", &flag);
        ll l, r, val;
        if (flag == 2) {
            scanf("%lld%lld", &l, &r);
            printf("%lld\n", query_tree(1, 1, n, l, r));
        }
        else {
            scanf("%lld%lld%lld", &l, &r, &val);
            update_section(1, 1, n, l, r, val);
        }
    }
    return 0;

}