Create 0043-multiply-strings.kt

Author: a93a

kotlin/0043-multiply-strings.kt

@@ -0,0 +1,26 @@
+
+class Solution {
+    fun multiply(num1: String, num2: String): String {
+        if (num1=="0" || num2=="0") return "0"
+
+        val sum = IntArray(num1.length + num2.length)
+        val n1 = num1.reversed()
+        val n2 = num2.reversed()
+
+        for (i in 0 until n1.length) {
+            for (j in 0 until n2.length) {
+                var temp = (n1[i] - '0') * (n2[j] - '0') + sum[i + j]
+                sum[i + j + 1] += temp / 10
+                sum[i + j] = temp % 10
+            }
+        }
+
+        return StringBuilder().apply {
+            for(i in sum.lastIndex downTo 0) {
+                if (this.length == 0 && sum[i] == 0) continue 
+                this.append(sum[i])
+            }
+        }.toString()
+        
+    }
+}