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Author: Chihung Yu

144 Binary Tree Preorder Traversal My Submissions Question.js

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+// Leetcode #144
+// Language: Javascript
+// Problem: https://leetcode.com/problems/binary-tree-preorder-traversal/
+// Author: Chihung Yu
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[]}
+ */
+
+var preorderTraversal = function(root) {
+    var result = [];
+    
+    traverse(root, result);
+    
+    return result;
+};
+
+function traverse(node, result) {
+    if(!node) {
+        return;
+    }
+    
+    result.push(node.val);
+    
+    traverse(node.left, result);
+    traverse(node.right, result);
+}

268 Missing Number.js

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+// Leetcode 268
+// Language: Javascript
+// Problem: https://leetcode.com/problems/missing-number/
+// Author: Chihung Yu
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+
+ var missingNumber = function(nums) {
+    var res = 0;
+    
+    // nums = [0, 1, 3, 4, 5]
+    // index go from 1 to 5
+    // res starts with 0
+    // perform xor so that index and num will cancel out leaving the odd num alone
+    for(var i = 1; i <= nums.length; i++) {
+        res = res ^ i ^ nums[i - 1];
+    }
+ 
+    return res;
+};

27 Remove Element.js

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+// Leetcode 27
+// Language: Javascript
+// Problem: https://leetcode.com/problems/remove-element/
+// Author: Chihung Yu
 /**
  * @param {number[]} A
  * @param {number} elem

318 Maximum Product of Word Lengths My Submissions Question.js

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+// Leetcode 318
+// Language: Javascript
+// Problem: https://leetcode.com/problems/maximum-product-of-word-lengths/
+// Author: Chihung Yu
+/**
+ * @param {string[]} words
+ * @return {number}
+ */
+var maxProduct = function(words) {
+    var processed = [];
+    
+    for(var i = 0; i < words.length; i++) {
+        processed.push(compute(words[i]));
+    }
+
+    var result = [];
+    var max = 0;
+    
+    for(i = 0; i < words.length; i++) {
+        for(var j = i + 1; j < words.length; j++) {
+            if((processed[i] & processed[j]) === 0) {
+                var cur = words[i].length * words[j].length;
+                
+                if(cur > max) {
+                    max = cur;
+                }
+            }
+        }
+    }
+    
+    return max;
+};
+
+function compute(word) {
+    var val = 0;
+    var base = "a".charCodeAt(0);
+    
+    for(i = 0; i < word.length; i++){
+        val |= (1 << (word.charCodeAt(i) - base));
+        
+    }
+    return val;
+}