POJ1700 贪心

n个人过河，船每次只能坐两个人，船载每个人过河的所需时间不同，回来的时间单独计算，问最快的过河时间。

贪心保证每次把最慢和次慢的2个人运到对岸。

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		new Task().solve() ;
	}
}

class Task{
	InputReader in = new InputReader(System.in) ;
	PrintWriter out = new PrintWriter(System.out) ;

	long sum(int left , int right , int[] num){
		if(left == right || right == left + 1) return num[right] ;
		else if(right == left + 2) return num[left] + num[left+1] + num[left+2] ;
		else{
		    long way1 = (num[right] + num[left] + num[right-1] + num[left]) ; //（最慢最快）->最快回->（次慢最快）->最快回
		    long way2 = (num[left+1] + num[left+1] + num[right] + num[left]) ; //（次快最快）->次快回->（最慢次慢）->最快回
			return Math.min(way1, way2) + sum(left , right-2 , num) ;
		}
	}
	
	void solve(){
		int t = in.nextInt() ;
		while(t-- > 0){
			int n = in.nextInt() ; 
			int[] num = new int[n] ;
			for(int i = 0 ; i < n ; i++) num[i] = in.nextInt() ; 
			Arrays.sort(num) ;
			out.println(sum(0, n-1 , num)) ;
		}
		out.flush() ;
	}

}

class InputReader {    
    public BufferedReader reader;    
    public StringTokenizer tokenizer;    
    
    public InputReader(InputStream stream) {    
        reader = new BufferedReader(new InputStreamReader(stream), 32768);    
        tokenizer = new StringTokenizer("");    
    }    
    
    private void eat(String s) {    
        tokenizer = new StringTokenizer(s);    
    }    
    
    public String nextLine() {    
        try {    
            return reader.readLine();    
        } catch (Exception e) {    
            return null;    
        }    
    }    
    
    public boolean hasNext() {    
        while (!tokenizer.hasMoreTokens()) {    
            String s = nextLine();    
            if (s == null)    
                return false;    
            eat(s);    
        }    
        return true;    
    }    
    
    public String next() {    
        hasNext();    
        return tokenizer.nextToken();    
    }    
    
    public int nextInt() {    
        return Integer.parseInt(next());    
    }    
    
    public long nextLong() {    
        return Long.parseLong(next());    
    }    
    
    public double nextDouble() {    
        return Double.parseDouble(next());    
    }    
    
    public BigInteger nextBigInteger() {    
        return new BigInteger(next());    
    }    
    
}