题解 | #剩下的树#

#include <iostream>

using namespace std;

int main()
{
    int L,M,sum;
    int minNum,maxNum;
    int tree[10001];
    for(int i=0;i<10001;i++){
        tree[i]=1;
    }
    scanf("%d %d",&L,&M);
    sum=L+1;
    while(M>0){
            scanf("%d %d",&minNum,&maxNum);
        for(int j=minNum;j<maxNum+1;j++){
            if(tree[j]==1){
                sum--;
                tree[j]=0;
            }
        }

        M--;
     }
     printf("%d",sum);
}