update

Author: Chihung Yu

15 3Sum.js

@@ -33,8 +33,8 @@ var threeSum = function(nums) {
 
     for(var i = 0; i < len-2; i++){
 
-        if(i === 0 || nums[i] > nums[i-1]){ // very important, same as line 40, remove duplicate as 111 will only run once 1-> rather tan 1 1 1
-            target = 0 - nums[i];
+        if(i === 0 || nums[i] > nums[i-1]){ // very important, same as line 40, remove duplicate as 111 will only run once 1-> rather than 1 1 1
+            var target = 0 - nums[i];
 
             j = i + 1;
             k = len - 1;

158 Read N Characters Give Read4 II - Call Multiple Times.js

@@ -63,3 +63,36 @@ var solution = function(read4) {
         return numChrRead;
     };
 };
+
+var solution = function(read4) {
+    /**
+     * @param {character[]} buf Destination buffer
+     * @param {number} n Number of characters to read
+     * @return {number} The number of actual characters read
+     */
+    var read4Buff = [];
+    var read4NumCharRead = 0;
+    var read4Remain = 0;
+    
+    return function(buf, n) {
+        var numCharRead = 0;
+        
+        // Need to run read4 N times to get n char
+        while(numCharRead < n) {
+            // If everything is already read in read4 buffer, re-read
+            if (read4NumCharRead === read4Remain) {
+                read4NumCharRead = 0;
+                read4Remain = read4(read4Buff); 
+            }
+            while(read4NumCharRead < read4Remain && numCharRead < n) {
+                buf[numCharRead++] = read4Buff[read4NumCharRead++];
+            }
+            if (read4Remain < 4) {
+                break;
+            }
+            
+        }
+        
+        return numCharRead;    
+    };
+};

159 Longest Substring with At Most Two Disctinct Characters.js

@@ -64,7 +64,6 @@ var lengthOfLongestSubstringTwoDistinct = function(s) {
         if (map.size === 2 && map.get(c) === undefined) {
             var curStr;
             if (i - start > maxLen) {
-                curStr = s.substring(start, i);
                 maxLen = i - start;
             }
             var leftMost = s.length;

66 Plus One.js

@@ -2,6 +2,35 @@
  * @param {number[]} digits
  * @return {number[]}
  */
+
+// Time complexity : \mathcal{O}(N)O(N) since it's not more than one pass along the input list.
+
+// Space complexity : \mathcal{O}(1)O(1).
+var plusOne = function(digits) {
+    var carry = 1;
+    for(var i = digits.length - 1; i > -1; i--) {
+        var d = digits[i];
+        var sum = d + carry;
+        if (sum === 10) {
+            digits[i] = 0;
+            carry = 1;
+        } else {
+            digits[i] = sum;
+            carry = 0; // can directly return since it will not trigger the carry unshift at the end.
+            break;
+        }
+    }
+    
+    if (carry === 1) {
+        digits.unshift(carry);
+    }
+    
+    return digits;
+};
+
+
+
+
 var plusOne = function(digits) {
     for(var i = digits.length; i--;){
         digits[i] = 1 + digits[i];