solves interleaving strings in java

anishLearnsToCode · anishLearnsToCode · commit b1246c472508 · 2022-05-23T19:56:29.000+02:00
diff --git a/README.md b/README.md
@@ -89,7 +89,7 @@
 |  94  | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal)                                                              |                       [![Java](assets/java.png)](src/BinaryTreeInorderTraversal.java) [![Python](assets/python.png)](python/binary_tree_inorder_traversal.py)                        |                                                                                                                                   |
 |  95  | [Unique Binary Search Trees II](https://leetcode.com/problems/unique-binary-search-trees-ii)                                                              |                                                            [![Java](assets/java.png)](src/UniqueBinarySearchTreesII.java)                                                            |                                                                                                                                   |
 |  96  | [Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees)                                                                    |                                                             [![Java](assets/java.png)](src/UniqueBinarySearchTrees.java)                                                             |                                                                                                                                   |
-|  97  | [Interleaving String](https://leetcode.com/problems/interleaving-string)                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |
+|  97  | [Interleaving String](https://leetcode.com/problems/interleaving-string)                                                                                  |                                                               [![Java](assets/java.png)](src/InterleavingString.java)                                                                |                                                                                                                                   |
 |  98  | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree)                                                                  |                                                            [![Java](assets/java.png)](src/ValidateBinarySearchTree.java)                                                             |                                                                                                                                   |
 |  99  | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree)                                                                    |                                                                                                                                                                                      |                                                                                                                                   |
 | 100  | [Same Tree](https://leetcode.com/problems/same-tree)                                                                                                      |                                          [![Java](assets/java.png)](src/SameTree.java) [![Python](assets/python.png)](python/same_tree.py)                                           |                                                                                                                                   |
@@ -281,6 +281,8 @@
 | 349  | [Intersection of 2 Arrays](https://leetcode.com/problems/intersection-of-two-arrays)                                                                      |                            [![Java](assets/java.png)](src/IntersectionOfTwoArrays.java) [![Python](assets/python.png)](python/intersection_of_2_array.py)                            |                                                                                                                                   |
 | 350  | [Intersection of 2 Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii)                                                                |                         [![Java](assets/java.png)](src/IntersectionOfTwoArraysII.java) [![Python](assets/python.png)](python/intersection_of_2_arrays_II.py)                         |                                                                                                                                   |
 | 351  | 🔒 [Android Unlock Patterns](https://leetcode.com/problems/android-unlock-patterns)                                                                       |                                                                                                                                                                                      |                                                                                                                                   |
+| 355  | [Design Twitter](https://leetcode.com/problems/design-twitter)                                                                                            |                                                                                                                                                                                      |                                                                                                                                   |
+| 357  | [Count Numbers with Unique Digits](https://leetcode.com/problems/count-numbers-with-unique-digits)                                                        |                                                                                                                                                                                      |                                                                                                                                   |
 | 359  | 🔒 [Logger Rate Limiter](https://leetcode.com/problems/logger-rate-limiter)                                                                               |                                                                                                                                                                                      |                                                                                                                                   |
 | 367  | [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square)                                                                                |                                 [![Java](assets/java.png)](src/IsPerfectSquare.java) [![Python](assets/python.png)](python/valid_perfect_square.py)                                  |                                                                                                                                   |
 | 374  | [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower)                                                                |                         [![Java](assets/java.png)](src/GuessNumberHigherOrLower.java) [![Python](assets/python.png)](python/guess_number_higher_or_lower.py)                         |                                                                                                                                   |
diff --git a/src/InterleavingString.java b/src/InterleavingString.java
@@ -1,15 +1,34 @@
-public class InterleavingString {
-    public static void main(String[] args) {
-        System.out.println(isInterleave("aabcc", "dbbca", "aadbbcbcac"));
-    }
+// https://leetcode.com/problems/interleaving-string
+// T: O(n * m)
+// S: O(min(m, n))
 
-    public static boolean isInterleave(String s1, String s2, String s3) {
+public class InterleavingString {
+    public boolean isInterleave(String s1, String s2, String s3) {
         if (s1.length() + s2.length() != s3.length()) return false;
-        for (int i = 0, j = 0, t = 0 ; i <= s1.length() && j <= s2.length() && t < s3.length() ; t++) {
-            if (i < s1.length() && s3.charAt(t) == s1.charAt(i)) i++;
-            else if (j < s2.length() && s3.charAt(t) == s2.charAt(j)) j++;
-            else return false;
+        if (s1.length() < s2.length()) {
+            String temp = s1;
+            s1 = s2;
+            s2 = temp;
         }
-        return true;
+
+        final int rows = s1.length() + 1, columns = s2.length() + 1;
+        final boolean[] dp = new boolean[columns];
+
+        for (int row = 0 ; row < rows ; row++) {
+            for (int column = 0 ; column < columns ; column++) {
+                if (row == 0 && column == 0) {
+                    dp[column] = true;
+                } else if (row == 0) {
+                    dp[column] = dp[column - 1] && s2.charAt(column - 1) == s3.charAt(row + column - 1);
+                } else if (column == 0) {
+                    dp[column] = dp[column] && s1.charAt(row - 1) == s3.charAt(row + column - 1);
+                } else {
+                    dp[column] = (s1.charAt(row - 1) == s3.charAt(row + column - 1) && dp[column])
+                            || (s2.charAt(column - 1) == s3.charAt(row + column - 1) && dp[column - 1]);
+                }
+            }
+        }
+
+        return dp[columns - 1];
     }
 }
