#include<bits/stdc++.h>
using namespace std;
int main(){
int a,b,ans=1;
int t,w;
cin>>a>>b;
int x[a+1]={0};
for(int i=0;i<b;i++){
cin>>t>>w;
for(int i=t;i<=w;i++){
//cout<<i<<endl;
x[i]=1;
}
}
for(int i=1;i<=a;i++){
if(x[i]==0){
//cout<<"x"<<i<<"x"<<endl;
ans++;
}else{
//cout<<"0";
}
}
cout<<ans;
return 0;
}
```
by gordon321 @ 2023-06-09 14:04:57
```c
#include<bits/stdc++.h>
using namespace std;
int main(){
int a,b,ans=1;
int t,w;
cin>>a>>b;
int x[a+1]={0};
for(int i=0;i<b;i++){
cin>>t>>w;
for(int i=t;i<=w;i++){
//cout<<i<<endl;
x[i]=1;
}
}
for(int i=1;i<=a;i++){
if(x[i]==0){
//cout<<"x"<<i<<"x"<<endl;
ans++;
}else{
//cout<<"0";
}
}
cout<<ans;
return 0;
}
```
by gordon321 @ 2023-06-09 14:05:29
这个题是从0开始算的，a[0]也有颗树
by nsu22010220307 @ 2023-07-20 10:28:58