競プロ典型 90 問 / Q048

Q048.cs

using System;
using System.Linq;

class Q048
{
	static int[] Read() => Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
	static (int, int) Read2() { var a = Read(); return (a[0], a[1]); }
	static long[] ReadL() => Array.ConvertAll(Console.ReadLine().Split(), long.Parse);
	static void Main()
	{
		var (n, k) = Read2();
		Console.WriteLine(new bool[n].Select(_ => ReadL()).SelectMany(p => new[] { p[0] - p[1], p[1] }).OrderByDescending(x => x).Take(k).Sum());
	}
}

https://atcoder.jp/contests/typical90/submissions/23141428