[LeetCode]Maximum Gap

Given an unsorted array, find the maximum difference between the successive elements in its sorted form.

Try to solve it in linear time/space.

Return 0 if the array contains less than 2 elements.

You may assume all elements in the array are non-negative integers and fit in the 32-bit signed integer range.

Credits:
Special thanks to @porker2008 for adding this problem and creating all test cases.

桶排序

public class Solution {class Pair{int min;int max;Pair(int min,int max){this.min = min;this.max = max;}}    public int maximumGap(int[] num) {    if(num.length<=1) return 0;    int mn = num[0],mx = num[0];    int len = num.length;    for(int n:num){    mn = Math.min(mn, n);    mx = Math.max(mx, n);    }    if(mn== mx) return 0;    //桶间的间隔    int dist = (mx-mn)/len+1;    //每个pair就是一个桶，用来存储映射到该桶的最大与最小数    Pair[]buck = new Pair[len];    for(int n:num){    //映射的桶下标    int index = (n-mn)/dist;    if(buck[index]==null) {    buck[index]= new Pair(n,n);    continue;    }    Pair p = buck[index];    p.min = Math.min(n,p.min);    p.max = Math.max(n,p.max);    }    int preMax = buck[0].max;    int res = preMax-buck[0].min;    for(int i=1;i<buck.length;i++){    Pair p = buck[i];    if(p==null) continue;    res = Math.max(p.min-preMax, res);    preMax = p.max;    }    return res;    }}