Add valid parentheses solution

Author: hyunjung-choi

valid-parentheses/hyunjung-choi.kt

@@ -0,0 +1,27 @@
+/**
+ * 시간 복잡도: O(n)
+ * 공간 복잡도: O(n)
+ */
+
+class Solution {
+    fun isValid(s: String): Boolean {
+        if (s.length % 2 == 1) return false
+
+        val stack = Stack<Char>()
+        val pairs = mapOf(')' to '(', ']' to '[', '}' to '{')
+
+        for (char in s) {
+            when {
+                char in pairs -> {
+                    if (stack.isEmpty() || stack.pop() != pairs[char]) {
+                        return false
+                    }
+                }
+
+                else -> stack.push(char)
+            }
+        }
+
+        return stack.isEmpty()
+    }
+}