今日头条--笔试

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package test2;import java.util.Arrays;import java.util.Comparator;import java.util.LinkedList;/** * p为给定的二维平面整数点集。定义P中某店X，如果x满足p中 * 任意点都不在x的右上方区域内（横纵坐标都大于x），则称其中 * 为“最大的”。求出所有“最大的”点的集合。（所有点的横坐标和纵坐标都不重复，坐标轴范围在[0,1e9)内） */public class Problem_01_RightCorners {    public static class Node {        public int x;        public int y;        public Node(int x, int y) {            this.x = x;            this.y = y;        }    }    public static class MyComparator implements Comparator<Node> {        @Override        public int compare(Node o1, Node o2) {            if (o1.x != o2.x) {                return o1.x - o2.x;            } else {                return o2.y - o1.y;            }        }    }    public static LinkedList<Node> getRightCornerNodes1(int[] x, int[] y) {        int size = x.length;        LinkedList<Node> res = new LinkedList<>(); //定义一个node数组        Node[] nodes = new Node[size];        for (int i = 0; i < size; i++) {            nodes[i] = new Node(x[i], y[i]);  //放入所有的点        }        Arrays.sort(nodes, new MyComparator());         for (int i = 0; i < size; i++) {            boolean insert = true;            for (int j = 0; j < size; j++) {                if ((nodes[i].x < nodes[j].x) && (nodes[i].y < nodes[j].y)) {  //这种方法比较麻烦！                    insert = false;                }            }            if (insert) {                res.add(nodes[i]);            }        }        return res;    }    public static LinkedList<Node> getRightCornerNodes2(int[] x, int[] y) {        int size = x.length;        LinkedList<Node> res = new LinkedList<Node>();        Node[] nodes = new Node[size];        for (int i = 0; i < size; i++) {            nodes[i] = new Node(x[i], y[i]);        }        Arrays.sort(nodes, new MyComparator());        res.add(nodes[size - 1]);        int rightMaxY = nodes[size - 1].y;        for (int i = size - 2; i >= 0; i--) { //从右往左遍历 如果当前Y是最大的Y则 右上方无最大的点，并且排序的时候已经说过X小往大排序，Y从大到小排序。那么X相等的时候，那么比较的Y一定是X点最小的Y；            if (nodes[i].y >= rightMaxY) {                res.addFirst(nodes[i]);            }            rightMaxY = Math.max(rightMaxY, nodes[i].y);        }        return res;    }    public static int[] generateRandomArray(int size) {        int[] arr = new int[size];        for (int i = 0; i < size; i++) {            arr[i] = (int) (Math.random() * 1000);        }        return arr;    }    public static boolean isEqual(LinkedList<Node> list1, LinkedList<Node> list2) {        if (list1.size() != list2.size()) {            return false;        }        while (!list1.isEmpty()) {            Node node1 = list1.pollFirst();            Node node2 = list2.pollFirst();            if (node1.x != node2.x || node1.y != node2.y) {                return false;            }        }        return true;    }    public static void printArray(int[] x, int[] y) {        for (int i = 0; i < x.length; i++) {            System.out.print("(" + x[i] + "," + y[i] + ") ");        }        System.out.println();    }    public static void printLinkedList(LinkedList<Node> list) {        for (Node node : list) {            System.out.print("(" + node.x + "," + node.y + ") ");        }        System.out.println();    }    public static void main(String[] args) {        int testTime = 3000000;        for (int i = 0; i < testTime; i++) {            int size = 3;            int[] x = generateRandomArray(size);            int[] y = generateRandomArray(size);            LinkedList<Node> res1 = getRightCornerNodes1(x, y);            LinkedList<Node> res2 = getRightCornerNodes2(x, y);            if (!isEqual(res1, res2)) {                printArray(x, y);                printLinkedList(res1);                printLinkedList(res2);                break;            }        }    }}
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