Sync LeetCode submission Runtime - 0 ms (100.00%), Memory - 17.9 MB (…

…27.12%)

0028-find-the-index-of-the-first-occurrence-in-a-string/solution.py

@@ -1,18 +1,19 @@
-# Approach - Sliding Window
+# Approach 1: Sliding Window
+
+# Time: O(mn)
+# Space: O(1)
 
 class Solution:
     def strStr(self, haystack: str, needle: str) -> int:
-        if not needle:
-            return 0
-
-        n, k = len(haystack), len(needle)
-
-        if haystack[0 : k] == needle:
-            return 0
-
-        for i in range(k, n):
-            if haystack[i - k + 1 : i + 1] == needle:
-                return i - k + 1
+        m = len(needle)
+        n = len(haystack)
+
+        for window_start in range(n - m + 1):
+            for i in range(m):
+                if needle[i] != haystack[window_start + i]:
+                    break
+                if i == m - 1:
+                    return window_start
 
         return -1