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  • 给定一个数组,求如果排序之后,相邻两数的最大差值,要求时间复杂度O(N),且要求不能用非基于比较的排序。

    给定一个数组,求如果排序之后,相邻两数的最大差值,要求时间复杂度O(N),且要求不能用非基于比较的排序。

    import java.util.Arrays;
    
    public class MaximumDifferenceBetweenAdjacentNumbers{
            public static int maxGap(int[] nums){
                    if (nums == null || nums.length < 2) {
                            return 0;
                    }
    
                    int len = nums.length;
                    int min = Integer.MAX_VALUE;
                    int max = Integer.MIN_VALUE;
    
                    for (int i = 0; i < len; i++){
                            min = Math.min(min, nums[i]);
                            max = Math.max(max, nums[i]);
                    }
    
                    if (min == max){
                            return 0;
                    }
    
                    int bid = 0;
                    int[] maxs = new int[len + 1];
                    int[] mins = new int[len + 1];
                    boolean[] hasNum = new boolean[len + 1];
    
                    for (int i = 0; i < len; i++) {
                            bid = bucket(nums[i], len, min, max);
                            mins[bid] = hasNum[bid] ? Math.min(mins[bid], nums[i]) : nums[i];
                            maxs[bid] = hasNum[bid] ? Math.max(maxs[bid], nums[i]) : nums[i];
                            hasNum[bid] = true;
                    }
    
                    int res = 0;
                    int lastMax = maxs[0];
                    for (int i = 1; i < len + 1; i++) {
                            if (hasNum[i]){
                                    res = Math.max(res, mins[i] - lastMax);
                                    lastMax = maxs[i];
                            }
                    }
    
                    return res;
            }
    
            public static int bucket(long num, long len, long min, long max) {
                    return (int)((num - min) * len / (max - min));
            }
    
            public static int comparator(int[] nums) {
                    if(nums == null || nums.length < 2) {
                            return 0;
                    }
    
                    Arrays.sort(nums);
    
                    int res = Integer.MIN_VALUE;
                    for (int i = 1; i < nums.length; i++) {
                            res = Math.max(res, nums[i] - nums[i - 1]);
                    }
    
                    return res;
            }
    
            public static int[] generateRandomArray(int maxSize, int maxValue) {
                    int[] arr = new int[(int) ((maxSize+1) * Math.random())];
    
                    for (int i = 0; i < arr.length; i++) {
                            arr[i] = (int)((maxValue+1) * Math.random()) - (int) (maxValue) * Math.random();
                    }
    
                    return arr;
            }
    
            public static int[] copyArray(int[] arr) {
                    if (arr == null) {
                            return null;
                    }
    
                    int[] res = new int[arr.length];
                    for (int i = 0; i < arr.length; i++) {
                            res[i] = arr[i];
                    }
                    return res;
            }
    
            public static void main(String[] args) {
                    boolean succeed = true;
                    int testTime = 700000, maxSize = 100, maxValue = 100;
    
                    for (int i = 0; i < testTime; i++) {
                            int[] arr1 = generateRandomArray(maxSize, maxValue);
                            int[] arr2 = copyArray(arr1);
    
                            if (maxGap(arr1) != comparator(arr2)) {
                                    succeed = false;
                                    break;
                            }
                    }
    
                    System.out.println(succeed ? "Nice!" : "Fucking fucked!");
            }
    }
    
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  • 原文地址:https://www.cnblogs.com/AlexKing007/p/12338083.html
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