LeetCode 1057 Campus Bikes

思路

思路：使用priority queue并且重写比较器，(o1,o2)：当需要递增/最小堆时，o1

时间复杂度O(NM log(NM))
空间复杂度O(NM)

代码

class Triple {
    int workerIndex;
    int bikeIndex;
    int distance;
    Triple(int workerIndex, int bikeIndex, int distance) {
        this.workerIndex = workerIndex;
        this.bikeIndex = bikeIndex;
        this.distance = distance;
    }
}
class Solution {
    public int[] assignBikes(int[][] workers, int[][] bikes) {
        int[] result = new int[workers.length];
        PriorityQueue<Triple> pq = new PriorityQueue<Triple>(new Comparator<Triple>() {
            public int compare(Triple t1, Triple t2) {
                if (t1.distance == t2.distance) {
                    if (t1.workerIndex == t2.workerIndex) {
                        return t1.bikeIndex - t2.bikeIndex;
                    } else {
                        return t1.workerIndex - t2.workerIndex;
                    }
                } else {
                    return t1.distance - t2.distance;
                }
            }
        });
        boolean[] workerUsed = new boolean[workers.length];
        boolean[] bikeUsed = new boolean[bikes.length];
        
        for (int i = 0; i < workers.length; i++) {
            for (int j = 0; j < bikes.length; j++) {
                int dist = Math.abs(workers[i][0] - bikes[j][0])
                    + Math.abs(workers[i][1] - bikes[j][1]);
                pq.offer(new Triple(i, j, dist));
            }
        }
        
        while (!pq.isEmpty()) {
            Triple cur = pq.poll();
            int wIndex = cur.workerIndex, bIndex = cur.bikeIndex;
            if (workerUsed[wIndex] || bikeUsed[bIndex]) {
                continue;
            }
            result[wIndex] = bIndex;
            workerUsed[wIndex] = true;
            bikeUsed[bIndex] = true;
        }
        return result;
    }
}