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This approach involves detecting the start and end of each range by iterating through the array sequentially. You remember the start of a potential range and adjust the range's end as long as consecutive numbers are found. When a break in consecutiveness occurs, you fix the end of the current range and start a new one.
Time Complexity: O(n)
Space Complexity: O(n)
1
2function summaryRanges(nums) {
3 const result = [];
4 let i = 0;
5 while (i < nums.length) {
6 let start = i;
7 while (i + 1 < nums.length && nums[i] + 1 === nums[i + 1]) {
8 i++;
9 }
10 if (start === i) {
11 result.push(`${nums[start]}`);
12 } else {
13 result.push(`${nums[start]}->${nums[i]}`);
14 }
15 i++;
16 }
17 return result;
18}
19The JavaScript solution is implemented using a loop to identify ranges. It employs backticks for easy string interpolation when creating the range strings. Result is returned as an array of strings.
This approach utilizes a two-pointer method where one pointer marks the beginning of a new range, and another pointer (or the loop index itself) expands the range as far as possible until the next number isn't consecutive. Once a sequence ends, if numbers are the same, it is a single-element range; otherwise, a range connecting two different numbers is formed.
Time Complexity: O(n)
Space Complexity: O(n)
1using System;
using System.Collections.Generic;
public class Solution {
public IList<string> SummaryRanges(int[] nums) {
List<string> result = new List<string>();
int i = 0;
while (i < nums.Length) {
int start = i;
int j = i;
while (j + 1 < nums.Length && nums[j] + 1 == nums[j + 1]) {
j++;
}
if (start == j) {
result.Add(nums[start].ToString());
} else {
result.Add(nums[start] + "->" + nums[j]);
}
i = j + 1;
}
return result;
}
}
The C# solution employs two pointers approach, where the first pointer marks a new range beginning, while the second loop adjusts as numbers follow each other. This method yields consistent performance and clarity.