题解 | 校门外的树

#include <iostream>
#include <vector>
using namespace std;

int PlantTree(int L,int M)
{
    vector<int>tree(L+1,0);
    int n = L+1;
    int l=0,r=0;
    while(M--)
    {
        cin >> l >> r;
        int count = l;
        for(int i=count;i<=r;i++)
        {
            if(tree[i] == 0)
            {
                tree[i] = 1;
                n--;
            }
            else continue;
        }
    }
    return n;
}

int main() {
    int L=0,M=0,count=0;
    cin >> L >> M;
    count = PlantTree(L,M);
    cout << count << endl;
}
// 64 位输出请用 printf("%lld")