feat: minimum-window-substring

Author: minji-go

minimum-window-substring/minji-go.java

@@ -0,0 +1,50 @@
+/**
+ * <a href="https://leetcode.com/problems/minimum-window-substring/">week9-5. minimum-window-substring</a>
+ * <li>Description: return the minimum window substring of s such that every character in t (including duplicates) is included in the window </li>
+ * <li>Topics: Hash Table, String, Sliding Window   </li>
+ * <li>Time Complexity: O(M+N), Runtime 23ms        </li>
+ * <li>Space Complexity: O(1), Memory 45.13MB       </li>
+ */
+class Solution {
+    public String minWindow(String s, String t) {
+        if (s.length() < t.length()) return "";
+
+        Map<Character, Integer> tmap = new HashMap<>();
+        for (char c : t.toCharArray()) {
+            tmap.put(c, tmap.getOrDefault(c, 0) + 1);
+        }
+
+        Map<Character, Integer> smap = new HashMap<>();
+        int left = 0, right = 0;
+        int tsize = tmap.size();
+        int ssize = 0;
+        int start = -1, end = s.length();
+
+        while (right < s.length()) {
+            char c = s.charAt(right++);
+            if (tmap.containsKey(c)) {
+                smap.put(c, smap.getOrDefault(c, 0) + 1);
+                if (smap.get(c).intValue() == tmap.get(c).intValue()) {
+                    ssize++;
+                }
+            }
+
+            while (ssize == tsize) {
+                if (right - left < end - start) {
+                    start = left;
+                    end = right;
+                }
+
+                char l = s.charAt(left++);
+                if (tmap.containsKey(l)) {
+                    smap.put(l, smap.get(l) - 1);
+                    if (smap.get(l).intValue() < tmap.get(l).intValue()) {
+                        ssize--;
+                    }
+                }
+            }
+        }
+
+        return start == -1 ? "" : s.substring(start, end);
+    }
+}