sgu 133. Border 貪心

133. Border

time limit per test: 0.25 sec. 
memory limit per test: 4096 KB

Along the border between states A and B there are N defence outposts. For every outpost k, the interval [Ak,Bk] which is guarded by it is known. Because of financial reasons, the president of country A decided that some of the outposts should be abandoned. In fact, all the redundant outposts will be abandoned. An outpost i is redundant if there exists some outpost j such that Aj<Ai and Bi<Bj. Your task is to find the number of redundant outposts.

Input

The first line of the input will contain the integer number N (1<=N<=16 000). N lines will follow, each of them containing 2 integers: Ak and Bk (0<= Ak < Bk <= 2 000 000 000), separated by blanks. All the numbers Ak will be different. All the numbers Bk will be different.

Output

You should print the number of redundant outposts.

Sample Input

5
0 10
2 9
3 8
1 15
6 11

Sample Output

3

刪除多餘區間

#include <bits/stdc++.h>

using namespace std;

struct node{
    int a;
    int b;
};

node no[16005];

bool cmp(node x,node y){
    if(x.a==y.a){
        return x.b>y.b;
    }
    return x.a<y.a;
}

void solve(){
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%d%d",&no[i].a,&no[i].b);
    }
    sort(no,no+n,cmp);

//    for(int i=0;i<n;i++){
//        cout<<no[i].a<<" "<<no[i].b<<endl;
//    }
    int ans=0;
    int maxx=no[0].b;
    for(int i=1;i<n;i++){
        if(no[i].b>maxx){
            maxx=no[i].b;
        }
        else{
            ans++;
        }
    }
    printf("%d",ans);


}

int main(){
    solve();
    return 0;
}