主要重在理解线段树,理解了怎么改都可以,还有以后不要直接抄模板,要写出自己想的一份代码

&代码：

#include <cstdio>
#include <bitset>
#include <iostream>
#include <set>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <map>
#include <queue>
#include <vector>
using namespace std;
#define INF 0x3f3f3f3f
#define ll long long
const int maxn = 1e5 + 7;
struct nd {int l, r, v, lz;
} seg[maxn << 2];
int n;
inline void pushup(int rt) {seg[rt].v = max(seg[rt << 1].v, seg[rt << 1 | 1].v);
}
void pushdown(int rt) {if(seg[rt].lz) {seg[rt << 1].lz += seg[rt].lz;seg[rt << 1 | 1].lz += seg[rt].lz;seg[rt << 1].v += seg[rt].lz;seg[rt << 1 | 1].v += seg[rt].lz;seg[rt].lz = 0;}
}
void bulid(int b = 1, int e = n, int rt = 1) {seg[rt].l = b;seg[rt].r = e;if(b == e) {seg[rt].v = 0;return ;}int m = b + e >> 1;bulid(b, m, rt << 1);bulid(m + 1, e, rt << 1 | 1);pushup(rt);
}
void update(int l, int r, int xx, int b = 1, int e = n, int rt = 1) {if(l <= b && e <= r) {seg[rt].lz += xx;seg[rt].v += xx;return ;}pushdown(rt);int m = b + e >> 1;if(l <= m)update(l, r, xx, b, m, rt << 1);if(r > m)update(l, r, xx, m + 1, e, rt << 1 | 1);pushup(rt);
}
int query(int l, int r, int b = 1, int e = n, int rt = 1) {if(l <= b && e <= r) {return seg[rt].v;}pushdown(rt);int m = b + e >> 1;int re = 0;if(l <= m)re = max(re, query(l, r, b, m, rt << 1));if(r > m)re = max(re, query(l, r, m + 1, e, rt << 1 | 1));return re;
}
int main() {freopen("E:1.in", "r", stdin);n = 10;bulid();update(3, 5, 1);update(3, 5, 1);update(3, 5, 1);update(5, 6, 1);update(2, 8, 1);printf("%d\n", query(1, 10));printf("%d\n", query(5, 6));printf("%d\n", query(1, 3));printf("%d\n", query(1, 2));for(int i = 0; i < 100; i++) {if(seg[i].l) {printf("id=%d [%d , %d] val = %d  lz = %d\n", i, seg[i].l, seg[i].r, seg[i].v, seg[i].lz);}}return 0;
}