[tigermint] WEEK 02 Solutions

climbing-stairs/tigermint.kt

@@ -0,0 +1,16 @@
+class Solution {
+    fun climbStairs(n: Int): Int {
+        if (n == 1) return 1
+        if (n == 2) return 2
+
+        val dp = IntArray(n + 1) { 0 }
+        dp[1] = 1
+        dp[2] = 2
+
+        for (i in 3 .. n) {
+            dp[i] = dp[i - 1] + dp[i - 2]
+        }
+
+        return dp[n]
+    }
+}

product-of-array-except-self/tigermint.kt

@@ -0,0 +1,34 @@
+// class Solution {
+//     fun productExceptSelf(nums: IntArray): IntArray {
+//         val prefixProduct = IntArray(nums.size) { _ -> 1 }
+//         val suffixProduct = IntArray(nums.size) { _ -> 1 }
+
+//         for (i in 1 until nums.size) {
+//            prefixProduct[i] = prefixProduct[i - 1] * nums[i - 1]
+//         }
+
+//         for (i in nums.size - 2 downTo 0) {
+//             suffixProduct[i] = suffixProduct[i + 1] * nums[i + 1]
+//         }
+
+//         return IntArray(nums.size) { prefixProduct[it] * suffixProduct[it] }
+//     }
+// }
+
+class Solution {
+    fun productExceptSelf(nums: IntArray): IntArray {
+        val answer = IntArray(nums.size) { _ -> 1 }
+
+        for (i in 1 until nums.size) {
+           answer[i] = answer[i - 1] * nums[i - 1]
+        }
+
+        var right = 1
+        for (i in nums.size - 1 downTo 0) {
+            answer[i] *= right
+            right *= nums[i]
+        }
+
+        return answer
+    }
+}

valid-anagram/tigermint.kt

@@ -0,0 +1,20 @@
+class Solution {
+    fun isAnagram(s: String, t: String): Boolean {
+        val sCharToCount = mutableMapOf<Char, Int>()
+        val tCharToCount = mutableMapOf<Char, Int>()
+
+        s.forEach { sCharToCount[it] = (sCharToCount[it] ?: 0) + 1 }
+        t.forEach { tCharToCount[it] = (tCharToCount[it] ?: 0) + 1 }
+
+        val sKeys: MutableSet<Char> = sCharToCount.keys
+        val tKeys: MutableSet<Char> = tCharToCount.keys
+
+        if (sKeys != tKeys) return false
+        sKeys.forEach {
+            if (sCharToCount[it] != tCharToCount[it]) {
+                return false
+            }
+        }
+        return true
+    }
+}