Create MinimumWindowSubstring

leetcode 76. Minimum Window Substring

Author: Anubhav-pandey004

src/main/java/com/thealgorithms/slidingwindow/MinimumWindowSubstring

@@ -0,0 +1,55 @@
+package com.thealgorithms.slidingwindow;
+
+/**
+ * The Longest Subarray with Sum Less Than or Equal to k algorithm finds the length
+ * of the longest subarray whose sum is less than or equal to a given value k.
+ *
+ * <p>
+ * Worst-case performance O(n)
+ * Best-case performance O(n)
+ * Average performance O(n)
+ * Worst-case space complexity O(1)
+ *
+ * @author https://github.com/Chiefpatwal
+ */
+class Solution {
+ public static String minWindow(String s, String t) {
+        if (s.length() < t.length()) return "";
+
+        HashMap<Character, Integer> tFreq = new HashMap<>();
+        for (char c : t.toCharArray()) {
+            tFreq.put(c, tFreq.getOrDefault(c, 0) + 1);
+        }
+
+        HashMap<Character, Integer> windowFreq = new HashMap<>();
+        int left = 0, right = 0, minLen = Integer.MAX_VALUE, count = 0;
+        String result = "";
+
+        while (right < s.length()) {
+            char c = s.charAt(right);
+            windowFreq.put(c, windowFreq.getOrDefault(c, 0) + 1);
+
+            if (tFreq.containsKey(c) && windowFreq.get(c).intValue() <= tFreq.get(c).intValue()) {
+                count++;
+            }
+
+            while (count == t.length()) {
+                if (right - left + 1 < minLen) {
+                    minLen = right - left + 1;
+                    result = s.substring(left, right + 1);
+                }
+                
+                char leftChar = s.charAt(left);
+                windowFreq.put(leftChar, windowFreq.get(leftChar) - 1);
+                
+                if (tFreq.containsKey(leftChar) && windowFreq.get(leftChar) < tFreq.get(leftChar)) {
+                    count--;
+                }
+                
+                left++;
+            }
+            right++;
+        }
+        return result;
+    }
+}