g0301_0400.s0338_counting_bits.Solution.kt Maven / Gradle / Ivy

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Kotlin-based LeetCode algorithm problem solutions, regularly updated

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package g0301_0400.s0338_counting_bits

// #Easy #Top_100_Liked_Questions #Dynamic_Programming #Bit_Manipulation #Udemy_Bit_Manipulation
// #Big_O_Time_O(num)_Space_O(num) #2022_09_27_Time_186_ms_(99.26%)_Space_38.8_MB_(89.71%)

class Solution {
    fun countBits(num: Int): IntArray {
        val result = IntArray(num + 1)
        var borderPos = 1
        var incrPos = 1
        for (i in 1 until result.size) {
            // when we reach pow of 2, reset borderPos and incrPos
            if (incrPos == borderPos) {
                result[i] = 1
                incrPos = 1
                borderPos = i
            } else {
                result[i] = 1 + result[incrPos++]
            }
        }
        return result
    }
}