LeetCode解題(20200627)

870. 優勢洗牌 田忌賽馬

/**
 * Copyright (C), 2018-2020
 * FileName: advantageCount870
 * Author:   xjl
 * Date:     2020/6/27 11:03
 * Description: 優勢洗牌
 */
package Sort;

import java.util.*;

public class advantageCount870 {

    public int[] advantageCount(int[] A, int[] B) {

        int[] sortedA = A.clone();
        Arrays.sort(sortedA);

        int[] sortedB = B.clone();
        Arrays.sort(sortedB);

        // assigned[b] = list of a that are assigned to beat b
        Map<Integer, Deque<Integer>> assigned = new HashMap();
        for (int b: B) {
            assigned.put(b, new LinkedList());
        }
        // remaining = list of a that are not assigned to any b
        Deque<Integer> remaining = new LinkedList();

        // populate (assigned, remaining) appropriately
        // sortedB[j] is always the smallest unassigned element in B
        int j = 0;
        for (int a: sortedA) {
            if (a > sortedB[j]) {
                assigned.get(sortedB[j++]).add(a);
            } else {
                remaining.add(a);
            }
        }

        // Reconstruct the answer from annotations (assigned, remaining)
        int[] ans = new int[B.length];
        for (int i = 0; i < B.length; ++i) {
            // if there is some a assigned to b...
            if (assigned.get(B[i]).size() > 0)
                ans[i] = assigned.get(B[i]).pop();
            else
                ans[i] = remaining.pop();
        } 
        return ans;
    }
}