longest substring without repeating chars

Author: jackietian

3 Longest Substring Without Repeating Characters.js

@@ -3,34 +3,95 @@
  * @return {number}
  */
 
-
-var lengthOfLongestSubstring = function(s) {
-    if(s === null || s.length === 0){
+var lengthOfLongestSubstring = function (s) {
+    if (s === null || s.length === 0) {
         return 0;
     }
-    
+
     var map = {};
     var len = 0;
     var maxLen = len;
     var start = 0;
 
     // scan from left to right.    
-    for(var i = start; i < s.length; i++){
+    for (var i = start; i < s.length; i++) {
         c = s[i];
 
-        if(map[c] !== undefined && map[c] >= start) {
+        if (map[c] !== undefined && map[c] >= start) {
             start = map[c] + 1; // start new search with repeated word's last location + 1
             len = i - start; // real length -> from for example 3 to 5 is 3, so it's 5-3+1 and + 1 happens later
         }
-        
+
         len++; // real length -> from for example 3 to 5 is 3, so it's 5-3+1 and + 1 happens later
-        
-        if(len > maxLen){
+
+        if (len > maxLen) {
             maxLen = len;
         }
-        
+
         map[c] = i;
     }
-    
+
     return maxLen;
-};
+};
+
+
+/**
+ * Input: "abcabcbb" 
+ * Output: 3 
+ * Explanation: The answer is "abc", with the length of 3. 
+ * 
+ * Input: "bbbbb" 
+ * Output: 1 
+ * Explanation: The answer is "b", with the length of 1.
+ * 
+ * Input: "pwwkew"
+ * Output: 3
+ * Explanation: The answer is "wke", with the length of 3. 
+    Note that the answer must be a substring, "pwke" is a subsequence and not a substring.
+ */
+
+const longestSubstring = (s) => {
+    /**
+     * start : 0
+     * end: 0
+     * map: {a, b ,c}
+     * 
+     * abcabcbb
+     * 
+     * size: 3
+     */
+    // empty string return 0
+    if (!s) return 0;
+
+    let start = 0,
+        end = 0;
+    const map = [];
+    let result = 0;
+
+    while (end < s.length) {
+        // loop through s and find the biggest size
+        // if(map.indexOf(s[end]) > -1) {
+        //     map.shift();
+        //     start++;
+        // }
+
+        while (map.indexOf(s[end]) > -1) {
+            map.shift();
+            start++;
+        }
+
+        map.push(s[end]);
+
+        end++;
+        // console.log(start, end, map);
+
+        result = Math.max(result, end - start);
+    }
+    return result;
+
+}
+
+
+console.log(longestSubstring('bbbb')); // 1
+console.log(longestSubstring('abcabcbb')); // 3
+console.log(longestSubstring('pwwkett')); // 4