【LeetCode】163.Missing Ranges(Medium)(带锁题)解题报告

【LeetCode】163.Missing Ranges(Medium)(带锁题)解题报告

题目地址：https://leetcode.com/problems/missing-ranges/（带锁题）

题目描述：

  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”].

  要化为long型，比如[2^32-1] 0 214748647 , [“0->214748646”],[“0->214748646”,”-214748648->2147483647”]

Solution:

//time : O(n)
//space : O(1)
class Solution {
public List<String> findMissingRanges(int[] nums,int lower, int upper) {
List<String> res = new ArrayList<>();
long alower = (long)lower,aupper = (long)upper;
for(int num : nums){
if(num == alower){
alower++;
}else if(alower < num){
if(alower + 1 == num){
res.add(String.valueOd(alower));
}else{
res.add(alower + "->" + (num-1));
}
alower = (long)num + 1;
}
}
if(alower == aupper) res.add(String.valueOf(alower));
else if(alower < aupper) res.add(alower + "->" + aupper);
return res;
}
}

Date：2018年2月20日