g0401_0500.s0415_add_strings.Solution.kt Maven / Gradle / Ivy

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Kotlin-based LeetCode algorithm problem solutions, regularly updated

There is a newer version: 1.28

package g0401_0500.s0415_add_strings

// #Easy #String #Math #Simulation #Data_Structure_II_Day_6_String
// #2022_12_06_Time_296_ms_(76.00%)_Space_36_MB_(84.00%)

class Solution {
    fun addStrings(num1: String, num2: String): String {
        var endNum1 = num1.length - 1
        var endNum2 = num2.length - 1
        val res = StringBuilder()
        var carry = 0
        var sum: Int
        while (endNum1 >= 0 || endNum2 >= 0) {
            val a = if (endNum1 >= 0) num1[endNum1] - '0' else 0
            val b = if (endNum2 >= 0) num2[endNum2] - '0' else 0
            sum = (a + b + carry) % 10
            carry = (a + b + carry) / 10
            res.append(sum)
            endNum1--
            endNum2--
        }
        if (carry != 0) {
            res.append(carry)
        }
        return res.reverse().toString()
    }
}