```cpp
#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
int main() {
int l, m, mn, mx, sum = 0, kk[10005] = {0};
cin >> l >> m;
for (int i = 0; i < m; i++) {
cin >> mn >> mx;
for (int i = mn; i <= mx; i++) {//对被访问的树标记为1，未访问的树默认为0
kk[i] = 1;
}
}
for (int i = 0; i <= l; i++) {//统计没有被访问的树的数目
if (!kk[i])sum++;
}
cout << sum;
return 0;
}
```
可以参考一下
by Silkage_x @ 2023-03-05 09:31:12