LeetCode Missing Ranges [LeetCode Book Problem]

Given a sorted integer array where the range of elements are [lower, upper] inclusive, return its missing ranges.

For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74", "76->99"].

思路分析：这题基本就是考察双指针的应用，从lower-1开始，遍历nums数组找出missing range，可以利用pre和cur一前一后两个指针移动实现。注意lower和upper的处理，lower可以比nums中最小的数大，，upper可以比nums中最大的数小，所以考虑要周全。

参考Code（Book中的题目）

public List<String> findMissingRanges(int[] nums, int lower, int upper) {List<String> res = new ArrayList<String>();int pre = lower – 1;for(int i = 0; i < nums.length; i++){if(i == nums.length){cur = upper + 1;} else cur = nums[i];if(cur – pre >= 2){int missStart = pre + 1;int missEnd = cur – 1;if(missEnd == missStart) res.add(missEnd);else res.add(missStart + "->" + missEnd);pre = cur;} else {pre = cur;}}return res;}

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