[LeetCode164] Maximum Gap

最新推荐文章于 2023-02-12 13:52:00 发布

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本文提供了一种在线性时间复杂度和空间复杂度内解决寻找未排序数组在排序后最大连续元素差的问题的方法。适用于非负整数数组且数值范围在32位整数范围内。

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.

public int maximumGap(int[] nums) {
        if(nums.length <2) return 0;
        if(nums.length ==2) {
            return Math.abs(nums[0]-nums[1]);
        }
        int maxValue = nums[0];
        int minValue = nums[0];
        for(int i=1; i<nums.length; i++){
            maxValue = (maxValue> nums[i])? maxValue:nums[i];
            minValue = (minValue< nums[i])? minValue:nums[i];
        }
        int avGap = (maxValue-minValue) / (nums.length-1);
        int bucketCount = 0;
        if(avGap == 0){
            return maxValue-minValue;
        }else {
            bucketCount = (maxValue-minValue) / avGap;
        }
        //<min,max>, initiate map
        List<Node> bucketMap = new ArrayList<>();
        for(int i=0;i<=bucketCount;i++){
            bucketMap.add(new Node(Integer.MAX_VALUE, Integer.MIN_VALUE));
        }
        //every bucket min&max
        for(int i=0;i<nums.length;i++){
            int index = (nums[i]-minValue)/avGap;
            int tempMax = (bucketMap.get(index).max<nums[i])?nums[i]:bucketMap.get(index).max;
            int tempMin = (bucketMap.get(index).min>nums[i])?nums[i]:bucketMap.get(index).min;
            bucketMap.get(index).setValue(tempMin, tempMax);
//            bucketMap.add(index, new Node(tempMin, tempMax));
        }
        //find maximum
        int maxGap = 0;
        int maxLeft = bucketMap.get(0).max;
        for(int i=1;i<=bucketCount;i++){
            Node n1 = bucketMap.get(i);
            if(n1.min!=Integer.MAX_VALUE){
                maxGap = Math.max(maxGap, n1.min-maxLeft);
                maxLeft = n1.max;
            }
        }
        return maxGap;
    }
	class Node {
	    int min;
	    int max;
	    public Node(int min, int max){
	        this.min = min;
	        this.max = max;
	    }
	    public void setValue(int min,int max){
	        this.max = max;
	        this.min = min;
	    }
	}