g0201_0300.s0228_summary_ranges.Solution.kt Maven / Gradle / Ivy
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Kotlin-based LeetCode algorithm problem solutions, regularly updated
package g0201_0300.s0228_summary_ranges
// #Easy #Array #2022_10_26_Time_169_ms_(91.89%)_Space_34_MB_(95.95%)
class Solution {
fun summaryRanges(nums: IntArray): List {
val ranges: MutableList = ArrayList()
if (nums.size == 0) {
return ranges
}
// size of array
val n = nums.size
// start of range
var a = nums[0]
// end of range
var b = a
val strB = StringBuilder()
for (i in 1 until n) {
// we need to make a decision if the next element
// will expand the range
// i starts at 1, not 0, because 1 is the next
// candidate for expanding the range
if (nums[i] != b + 1) {
// only when our next element does not expand the range
// do we add the range a->b to our list of ranges
strB.append(a)
if (a != b) {
strB.append("->").append(b)
}
ranges.add(strB.toString())
// since nums[i] is not accounted for by our range a->b
// because nums[i] is not b+1, we need to set a and b
// to this new range start point of bigger than b+1
// maybe it is b+2? b+3? b+4? all we know is it is not b+1
a = nums[i]
b = a
// Reset string builder
strB.setLength(0)
} else {
// if the next element expands our range we do so
b++
}
}
// the only range that is not accounted for at this point is the last range
// if our a and b are not equal then we add the range accordingly
strB.append(a)
if (a != b) {
strB.append("->").append(b)
}
ranges.add(strB.toString())
return ranges
}
}