SummaryRanges228.kt

package easy

import kotlin.math.abs

/*
You are given a sorted unique integer array nums.

Return the smallest sorted list of ranges that cover all the numbers in the array exactly. That is, each element of nums is covered by exactly one of the ranges, and there is no integer x such that x is in one of the ranges but not in nums.

Each range [a,b] in the list should be output as:

"a->b" if a != b
"a" if a == b

Example 1:

Input: nums = [0,1,2,4,5,7]
Output: ["0->2","4->5","7"]
Explanation: The ranges are:
[0,2] --> "0->2"
[4,5] --> "4->5"
[7,7] --> "7"
Example 2:

Input: nums = [0,2,3,4,6,8,9]
Output: ["0","2->4","6","8->9"]
Explanation: The ranges are:
[0,0] --> "0"
[2,4] --> "2->4"
[6,6] --> "6"
[8,9] --> "8->9"
Example 3:

Input: nums = []
Output: []
Example 4:

Input: nums = [-1]
Output: ["-1"]
 */
fun summaryRanges(nums: IntArray): List<String> {
    if(nums.isEmpty())
        return emptyList()
    val result= mutableListOf<String>()
    var begin=nums[0]
    var end=nums[0]
    for(i in 1 until nums.size)
    {

        if(Math.abs(nums[i] - nums[i-1]) >1)
        {
            end=nums[i-1]
            if(begin<end)
                result.add("$begin->$end")
            else
                result.add("$begin")
            begin=nums[i]
        }else
        {
            end=nums[i]
        }
    }
    if(begin<end)
        result.add("$begin->$end")
    else
        result.add("$begin")

    return result
}