p1

Author: Chihung Yu

159 Longest Substring with At Most Two Disctinct Characters.js

@@ -4,6 +4,9 @@
  * @param {string} s
  * @return {number}
  */
+
+ // Time O(N)
+ // Space O(1)
 var lengthOfLongestSubstringTwoDistinct = function(s) {
     var longestSubstr = "";
     var maxLength = 0;
@@ -15,15 +18,14 @@ var lengthOfLongestSubstringTwoDistinct = function(s) {
 
         // if map already contains two distrinct chars and the char is new to the map
         if(map.size > 1 && map.get(c) === undefined) {
-            var leftMost = s.length;
-              
             // Calc substring len before the new char
             if(i - start > maxLength) {
                 // Should not include i, since i is the new distinct char's index
                 longestSubstr = s.substring(start, i);
                 maxLength = longestSubstr.length;
             }
-            
+            // Find the left most char
+            var leftMost = s.length;            
             map.forEach((charIdx, key)=> {
                 if(charIdx < leftMost) {
                     leftMost = charIdx;
@@ -44,3 +46,43 @@ var lengthOfLongestSubstringTwoDistinct = function(s) {
 
     return maxLength;
 };
+
+
+
+
+/**
+ * @param {string} s
+ * @return {number}
+ */
+var lengthOfLongestSubstringTwoDistinct = function(s) {
+    var map = new Map();
+    var start = 0;
+    var maxLen = 0;
+    
+    for(var i = 0; i < s.length; i++) {
+        var c = s[i];
+        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;
+            map.forEach((charIdx, key) => {
+                if (charIdx < leftMost) {
+                    leftMost = charIdx;
+                }            
+            });
+            start = leftMost + 1;
+            map.delete(s[leftMost]);
+        }
+        
+        map.set(c, i);
+    }
+    
+    if (s.length - start > maxLen) {
+        maxLen = s.length - start;
+    }
+    
+    return maxLen;
+};

48 Rotate Image.js

@@ -71,3 +71,42 @@ var swap = function(matrix, i1, j1, i2, j2) {
     matrix[i2][j2] = aux;
 };
 
+
+
+
+/**
+ * @param {number[][]} matrix
+ * @return {void} Do not return anything, modify matrix in-place instead.
+ */
+var rotate = function(matrix) {
+    rotateDiagonal(matrix);
+    rotateRow(matrix);
+};
+
+var swap = function(matrix, x1, y1, x2, y2) {
+    var temp = matrix[x1][y1];
+    matrix[x1][y1] = matrix[x2][y2];
+    matrix[x2][y2] = temp;
+}
+
+var rotateRow = function(matrix) {
+    for(var i = 0; i < matrix.length; i++) {
+        var row = matrix[i];
+        var start = 0;
+        var end = matrix[i].length - 1;
+        
+        while(start < end) {
+            swap(matrix, i, start, i, end);
+            start++;
+            end--;
+        }
+    }
+}
+
+var rotateDiagonal = function(matrix) {
+    for(var i = 0; i < matrix.length; i++) {
+        for(var j = i; j < matrix.length; j++) {
+            swap(matrix, i, j, j, i);
+        }
+    }
+}