砍树问题

 

#include<iostream>using namespace std;int main(){int l,m,num=0;//公路长度l,砍树区域个数m,剩余树的颗数num int *previous=new int[m];int *behind=new int[m];bool *judge=new bool[l];cin>>l>>m;bool judge2=true;for(int i=0;i<=l;i++){judge[i]=true;}for(int i=0;i<m;i++){cin>>previous[i]>>behind[i];if(previous[i]>behind[i]||previous[i]>l||behind[i]>l){cout<<"输入错误，previous[i]必须比behind[i]小，且均不大于l,请退出程序重新开始"<<endl;judge2=false;break;}for(int j=previous[i];j<=behind[i];j++){judge[j]=false;}}for(int k=0;k<=l;k++){if(judge[k]==true){num++;}}if(judge2==true){cout<<num;}delete previous;delete behind;delete judge;return 0;} 

//此题巧妙地运用了bool数组进行判断，然后计数，从而避免了计算