vault backup: 2022-07-14 10:02:54

OJ notes/pages/Leetcode Longest-Substring-Without-Repeating-Characters.md

@@ -3,7 +3,7 @@
 #### 2022-07-14 09:33
 
 > ##### Algorithms:
-> #algorithm 
+> #algorithm #Kadane_s_algorithm 
 > ##### Data structures:
 > #DS #string 
 > ##### Difficulty:
@@ -15,10 +15,12 @@
 
 ##### Related topics:
 ```expander
-tag:#<INSERT_TAG_HERE>
+tag:#Kadane_s_algorithm
 ```
- 
+
- 
+
+
+
 
 ##### Links:
 - [Link to problem](https://leetcode.com/problems/longest-substring-without-repeating-characters/)
@@ -56,12 +58,45 @@ Notice that the answer must be a substring, "pwke" is a subsequence and not a su
 ### Thoughts
 
 > [!summary]
-> This is a #
+> This is a #Kadane_s_algorithm 
 
-Initially, I thought of a lineal algorithm
+Initially, I thought of a kadane's algo, but implemented wrong.
+
+Then I figured out kadane's algorithm.
+
+similar to this one.
+[[Leetcode Best-Time-To-Buy-And-Sell-Stock]]
+
+The goal is making cur as small as possible, without duplicating
 
 ### Solution
 
+Kadane's algorithm
+
+```cpp
+class Solution {
+public:
+  int lengthOfLongestSubstring(string s) {
+    // Kadane's algorithm
+    vector<int> hMap(255, -1);
+
+    int cur = -1;
+    int localMax = 0;
+
+    for (int i = 0; i < s.length(); i++) {
+      if (hMap[s[i]] > cur) {
+        // If the element occurs again, reset
+        cur = hMap[s[i]];
+      }
+
+      hMap[s[i]] = i;
+      localMax = max(localMax, i - cur);
+    }
+    return localMax;
+  }
+};
+```
+
 Initial solution
 
 ```cpp