[C++] 2170 - 선 긋기

문제 링크 : https://www.acmicpc.net/problem/2170

2170번: 선 긋기

 

 

#include<iostream>
#include<algorithm>
#include<utility>
 
using namespace std;
 
typedef pair<int, int> pii;
 
pii P[1000005];
 
int main(void)
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
 
    int n;
    int v1, v2;
 
    cin >> n;
    for(int i = 0; i < n; ++i)
    {
        cin >> v1 >> v2;
        P[i] = pii(v1, v2);
    }
 
    sort(P, P+n);
 
    int ret = 0;
    
    ret = P[0].second - P[0].first;
    int pre = P[0].second;
 
    for(int i = 1; i < n; ++i)
    {
        if(P[i].first < pre && pre < P[i].second)
            ret += P[i].second - pre;
        else if(pre < P[i].first)
            ret += P[i].second - P[i].first;
        
        pre = max(pre, P[i].second);
        
    }
 
    cout << ret << endl;
 
    return 0;
}