归档 2016年2月

首先来看笔者遇到的一道面试题，阅读下面的代码并给出执行结果：

class Singleton {
    private static Singleton singleton = new Singleton();
    public static int counter1;
    public static int counter2 = 0;

    private Singleton() {
        counter1++;
        counter2++;
    }

    public static Singleton getInstance() {
        return singleton;
    }
}

public class TestSingleton {
    public static void main(String[] args) {
        Singleton s ...

题目描述：

LeetCode 335. Self Crossing

You are given an array x of n positive numbers. You start at point (0,0) and moves x[0] metres to the north, then x[1] metres to the west, x[2] metres to ...

题目描述：

LeetCode 334. Increasing Triplet Subsequence

Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.

Formally the function should:

Return true if there exists i, j, k
such that arr[i ...

题目描述：

LeetCode 332. Reconstruct Itinerary

Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK. Thus, the ...

数组洗牌是指将一个数组中的元素顺序打乱，随机重新排列。

算法实现思路如下：

按照下标从大到小的顺序遍历数组，记下标为i

遍历时生成范围[0, i]的随机数j，交换下标i与下标j的数组元素

参考：java.util.Collections类中的shuffle方法

Java代码：

public static void shuffle(int[] nums) {
    Random rnd = new Random();
    for (int i = nums.length - 1; i > 0; i--) {
        int j ...