1.
```cpp
for (int n = b[k][0]; n < b[k][1]; n++)
```
应为
```cpp
for (int n = b[k][0]; n <= b[k][1]; n++)
```
2.不应该把sum-1.
3.是从0到l，而不是从0到l-1！
~~验证码r8r8祭~~
by anke2017 @ 2024-02-28 13:05:08
@[ZJdog](/user/1282382)
~~验证码wbdj祭~~
by anke2017 @ 2024-02-28 13:05:56
```
#include<bits/stdc++.h>
using namespace std;
int main(){
int l,m;
cin >> l >> m;
int shen = l + 1;
int tr[shen] = {0};
while(m--){
int u,v;
cin >> u >> v;
for(int i = u;i <= v;i++){
if(tr[i] == 0){
tr[i] = 1;
shen -= 1;
}
}
}
cout << shen;
return 0;
}
```
by zhang0430 @ 2024-03-06 19:35:41