[Wan] Week 6

container-with-most-water/taewanseoul.ts

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+/**
+ * 11. Container With Most Water
+ * You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).
+ * Find two lines that together with the x-axis form a container, such that the container contains the most water.
+ * Return the maximum amount of water a container can store.
+ *
+ * Notice that you may not slant the container.
+ *
+ * https://leetcode.com/problems/container-with-most-water/description/
+ *
+ */
+
+// O(n) time
+// O(1) space
+function maxArea(height: number[]): number {
+  let l = 0;
+  let r = height.length - 1;
+  let max = 0;
+
+  while (l < r) {
+    max = Math.max(max, Math.min(height[l], height[r]) * (r - l));
+
+    if (height[l] < height[r]) {
+      l++;
+    } else {
+      r--;
+    }
+  }
+
+  return max;
+}

valid-parentheses/taewanseoul.ts

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+/**
+ * 20. Valid Parentheses
+ * Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
+ *
+ * An input string is valid if:
+ * 1. Open brackets must be closed by the same type of brackets.
+ * 2. Open brackets must be closed in the correct order.
+ * 3. Every close bracket has a corresponding open bracket of the same type.
+ *
+ * https://leetcode.com/problems/valid-parentheses/
+ *
+ */
+
+// O(n^2) time
+// O(1) space
+function isValid(s: string): boolean {
+  if (s.length % 2 === 1) return false;
+
+  while (
+    s.indexOf("()") !== -1 ||
+    s.indexOf("{}") !== -1 ||
+    s.indexOf("[]") !== -1
+  ) {
+    s = s.replace("()", "");
+    s = s.replace("{}", "");
+    s = s.replace("[]", "");
+  }
+
+  return s === "";
+}