线段树（模板

某大佬的模板#include <iostream>
#include <cstdio> 
typedef long long LL;
LL n, a[100005], d[270000], b[270000];
void build(LL l, LL r, LL p) {//建树 
  if (l == r) {
    d[p] = a[l];
    return;
  }
  LL m = (l + r) >> 1;
  build(l, m, p << 1), build(m + 1, r, (p << 1) | 1);
  d[p] = d[p << 1] + d[(p << 1) | 1];
}
void update(LL l, LL r, LL c, LL s, LL t, LL p) {//区间加数 
  if (l <= s && t <= r) {
    d[p] += (t - s + 1) * c, b[p] += c;
    return;
  }
  LL m = (s + t) >> 1;
  if (b[p])
    d[p << 1] += b[p] * (m - s + 1), d[(p << 1) | 1] += b[p] * (t - m),
        b[p << 1] += b[p], b[(p << 1) | 1] += b[p];
  b[p] = 0;
  if (l <= m) update(l, r, c, s, m, p << 1);
  if (r > m) update(l, r, c, m + 1, t, (p << 1) | 1);
  d[p] = d[p << 1] + d[(p << 1) | 1];
}
LL getsum(LL l, LL r, LL s, LL t, LL p) {//区间查询 
  if (l <= s && t <= r) return d[p];
  LL m = (s + t) >> 1;
  if (b[p])
    d[p << 1] += b[p] * (m - s + 1), d[(p << 1) | 1] += b[p] * (t - m),
        b[p << 1] += b[p], b[(p << 1) | 1] += b[p];
  b[p] = 0;
  LL sum = 0;
  if (l <= m) sum = getsum(l, r, s, m, p << 1);
  if (r > m) sum += getsum(l, r, m + 1, t, (p << 1) | 1);
  return sum;
}
int main() {
  std::ios::sync_with_stdio(0);
  LL q, i1, i2, i3, i4;
  std::cin >> n >> q;
  for (LL i = 1; i <= n; i++) std::cin >> a[i];
  build(1, n, 1);
  while (q--) {
    std::cin >> i1 >> i2 >> i3;
    if (i1 == 2)
      std::cout << getsum(i2, i3, 1, n, 1) << "\n";
    else
      std::cin >> i4, update(i2, i3, i4, 1, n, 1);
  }
  return 0;
}

　　

来源：https://www.cnblogs.com/liuxiangyu666/p/11403528.html