add more solution

Author: chihungyu1116

.gitignore

@@ -0,0 +1,2 @@
+facebook
+test.js

1 Two Sum.js

@@ -1,3 +1,21 @@
+// Given an array of integers, return indices of the two numbers such that they add up to a specific target.
+
+// You may assume that each input would have exactly one solution.
+
+// Example:
+// Given nums = [2, 7, 11, 15], target = 9,
+
+// Because nums[0] + nums[1] = 2 + 7 = 9,
+// return [0, 1].
+// UPDATE (2016/2/13):
+// The return format had been changed to zero-based indices. Please read the above updated description carefully.
+
+// Hide Company Tags LinkedIn Uber Airbnb Facebook Amazon Microsoft Apple Yahoo Dropbox Bloomberg Yelp Adobe
+// Hide Tags Array Hash Table
+// Hide Similar Problems (M) 3Sum (M) 4Sum (M) Two Sum II - Input array is sorted (E) Two Sum III - Data structure design
+
+
+
 /**
  * @param {number[]} nums
  * @param {number} target
@@ -6,19 +24,12 @@
 var twoSum = function(nums, target) {
     var hash = {};
 
-    for(var i = 0; i < nums.length; i++){
-        hash[nums[i]] = i;
-    }
-    
-    for(i = 0; i < nums.length; i++){
+    for(var i = 0; i < nums.length; i++) {
         var num = nums[i];
-        var diff = target - num;
-        if(hash[diff] !== undefined && hash[diff] !== i){
-            if(hash[diff] > i){
-                return [i+1, hash[diff]+1];
-            } else {
-                return [hash[diff]+1, i+1]
-            }
+        if(hash[num] !== undefined) {
+            return [hash[num], i]
+        } else {
+            hash[target - num] = i;
         }
     }
 

10 Regular Expresion Matching.js

@@ -19,21 +19,20 @@
 // isMatch("ab", ".*") → true
 // isMatch("aab", "c*a*b") → true
 
-
 /**
  * @param {string} s
  * @param {string} p
  * @return {boolean}
  */
 var isMatch = function(s, p) {
-    var m = s.length;
-    var n = p.length;
+        var sLen = s.length;
+    var pLen = p.length;
     var dp = [];
 
-    for(var i = 0; i <= m; i++) {
+    for(var i = 0; i <= sLen; i++) {
         var tmp = [];
 
-        for(var j = 0; j <= n; j++) {
+        for(var j = 0; j <= pLen; j++) {
             tmp.push(false);
         }
 
@@ -42,33 +41,33 @@ var isMatch = function(s, p) {
 
     dp[0][0] = true;
 
-    for(i = 0; i <= m; i++) {
-        for(j = 0; j <= n; j++) {
-            if(p[j-1] !== '.' && p[j-1] !== '*') {
-                if(i > 0 && s[i-1] === p[j-1] && dp[i-1][j-1]) {
+    for(i = 0; i <= sLen; i++) {
+        for(j = 0; j <= pLen; j++) {
+            if(p[j - 1] !== '.' && p[j - 1] !== '*') {
+                if(i > 0 && p[j - 1] === s[i - 1] && dp[i - 1][j - 1]) {
                     dp[i][j] = true;
                 }
-            } else if(p[j-1] === '.') {
-                if(i > 0 && dp[i-1][j-1]) {
-                  dp[i][j] = true;
+            } else if(p[j - 1] === '.') {
+                if(i > 0 && dp[i - 1][j - 1]) {
+                    dp[i][j] = true;
                 }
-            } else if(j > 1) { // '*' cannot be the first element      
-                if(dp[i][j-2]) { // 0 Occurance
-                  dp[i][j] = true;     
-                } else if(i > 0 && (p[j-2] == s[i-1] || p[j-2] == '.') && dp[i-1][j]) {
-
+            } else if(j > 1) { // '*' cannot be the first element
+                if(dp[i][j - 2]) { // 0 occurance
+                    dp[i][j] = true;
+                } else if(i > 0 && (p[j - 2] === s[i - 1] || p[j - 2] === '.') && dp[i - 1][j]) {
+                    
                   // example
                   // xa and xa* 
                   // s[i-1] === a
                   // p[j-2] === a
                   // a === a
                   // so we can now compare x, xa*
                   // and x here is dp[i-1][j]
-                    dp[i][j] = true; 
+                    dp[i][j] = true;
                 }
             }
         }
     }
 
-    return dp[m][n];
+    return dp[sLen][pLen];
 };

121 Best Time to Buy and Sell Stock.js

@@ -1,7 +1,21 @@
-// Leetcode 121
-// Language: Javascript
-// Problem: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
-// Author: Chihung Yu
+// Say you have an array for which the ith element is the price of a given stock on day i.
+
+// If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.
+
+// Example 1:
+// Input: [7, 1, 5, 3, 6, 4]
+// Output: 5
+
+// max. difference = 6-1 = 5 (not 7-1 = 6, as selling price needs to be larger than buying price)
+// Example 2:
+// Input: [7, 6, 4, 3, 1]
+// Output: 0
+
+// In this case, no transaction is done, i.e. max profit = 0.
+// Hide Company Tags Amazon Microsoft Bloomberg Uber Facebook
+// Hide Tags Array Dynamic Programming
+// Hide Similar Problems (M) Maximum Subarray (M) Best Time to Buy and Sell Stock II (H) Best Time to Buy and Sell Stock III (H) Best Time to Buy and Sell Stock IV (M) Best Time to Buy and Sell Stock with Cooldown
+
 /**
  * @param {number[]} prices
  * @return {number}

125 Valid Palindrome.js

@@ -36,5 +36,33 @@ var isPalindrome = function(s) {
         }
     }
 
+    return true;
+};
+
+
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+var isPalindrome = function(s) {
+    var head = 0;
+    var tail = s.length - 1;
+    
+    s = s.toLowerCase();
+    
+    while(head < tail) {
+        while(s[head] && !s[head].match(/[a-z0-9]/)) {
+            head++;
+        }
+        while(s[tail] && !s[tail].match(/[a-z0-9]/)) {
+            tail--;
+        }
+        if(head < tail && s[head] !== s[tail]) {
+            return false;
+        }
+        head++;
+        tail--;
+    }
+    
     return true;
 };

133 Clone Graph.js

@@ -57,4 +57,25 @@ var cloneGraph = function(graph) {
         }
         return newNode; 
     }   
+};
+
+
+var cloneGraph = function(graph) {
+    if(!graph) {
+        return graph;
+    } else {
+        return dfs(graph, {});
+    }
+    
+    function dfs(node, visited) {
+        var newNode = visited[node.label] = visited[node.label] || new UndirectedGraphNode(node.label);
+        
+        for(var i = 0; i < node.neighbors.length; i++) {
+            var neighbor = node.neighbors[i];
+            newNode.neighbors[i] = visited[neighbor.label] = visited[neighbor.label] || dfs(neighbor, visited);
+        }
+        
+        return newNode;
+    }
+    
 };

15 3Sum.js

@@ -1,3 +1,20 @@
+// Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.
+
+// Note: The solution set must not contain duplicate triplets.
+
+// For example, given array S = [-1, 0, 1, 2, -1, -4],
+
+// A solution set is:
+// [
+//   [-1, 0, 1],
+//   [-1, -1, 2]
+// ]
+// Hide Company Tags Amazon Microsoft Bloomberg Facebook Adobe
+// Hide Tags Array Two Pointers
+// Hide Similar Problems (E) Two Sum (M) 3Sum Closest (M) 4Sum (M) 3Sum Smaller
+
+
+
 /**
  * @param {number[]} nums
  * @return {number[][]}

157 Read N Characters Given Read4.js

@@ -0,0 +1,57 @@
+// The API: int read4(char *buf) reads 4 characters at a time from a file.
+
+// The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file.
+
+// By using the read4 API, implement the function int read(char *buf, int n) that reads n characters from the file.
+
+// Note:
+// The read function will only be called once for each test case.
+
+// Hide Company Tags Facebook
+// Hide Tags String
+// Hide Similar Problems (H) Read N Characters Given Read4 II - Call multiple times
+
+
+/**
+ * Definition for read4()
+ * 
+ * @param {character[]} buf Destination buffer
+ * @return {number} The number of characters read
+ * read4 = function(buf) {
+ *     ...
+ * };
+ */
+
+/**
+ * @param {function} read4()
+ * @return {function}
+ */
+var solution = function(read4) {
+    /**
+     * @param {character[]} buf Destination buffer
+     * @param {number} n Maximum number of characters to read
+     * @return {number} The number of characters read
+     */
+    return function(buf, n) {
+        var eof = false;
+        var total = 0;
+        var temp = Array(4);
+        
+        while(!eof && total < n) {
+            // read4 will populate temp with read characters, and return count ...
+            var count = read4(temp);
+        
+            if(count < 4) {
+                eof = true;
+            }
+            
+            count = Math.min(count, n - total);
+            
+            for(var i = 0; i < count; i++) {
+                buf[total++] = temp[i];
+            }
+        }
+        
+        return total;
+    };
+};

161 One Edit Distance.js

@@ -42,4 +42,40 @@ var isOneEditDistance = function(s, t) {
   }
 
   return found || s.length < t.length;
+};
+
+
+var isOneEditDistance = function(s, t) {
+    if(s.length > t.length) {
+        var tmp = s;
+        s = t;
+        t = tmp;
+    }
+    
+    if(t.length - s.length > 1) {
+        return false;
+    }
+    
+    
+    var i = 0;
+    var j = 0;
+    var diff = 0;
+    
+    while(i < s.length && j < t.length) {
+        if(s[i] !== t[j]) {
+            if(diff !== 0) {
+                return false;
+            }
+            diff++;
+            
+            if(t.length !== s.length) {
+                i--;
+            }
+        }
+        
+        i++;
+        j++;
+    }
+    
+    return diff === 1 || (t.length !== s.length && (t.length - j) === 1);
 };