WordSearch.java added

Author: Subham1999

.idea/workspace.xml

@@ -0,0 +1,66 @@
+package com.thealgorithm.backtracking;
+
+/**
+ * @author: Subham Santra
+ */
+public class WordSearch {
+  public boolean exist(char[][] board, String word) {
+    final int m = board.length;
+    final int n = board[0].length;
+    final boolean[][] taken = new boolean[m][n];
+
+    for (int i = 0; i < m; ++i) {
+      for (int j = 0; j < n; ++j) {
+        if (board[i][j] == word.charAt(0)) {
+          if (EXPLORE(board, i, j, m, n, 0, word, taken)) {
+            return true;
+          }
+        }
+      }
+    }
+
+    return false;
+  }
+
+  boolean EXPLORE(
+      char[][] board,
+      int i,
+      int j,
+      int m,
+      int n,
+      int wordCharIndex,
+      String word,
+      boolean[][] taken) {
+    if (wordCharIndex == word.length()) {
+      return true;
+    }
+
+    if (!((0 <= i && i < m) && (0 <= j && j < n))) {
+      return false;
+    }
+
+    if (taken[i][j]) {
+      return false;
+    }
+
+    boolean ans = false;
+
+    taken[i][j] = true;
+    if (board[i][j] == word.charAt(wordCharIndex)) {
+      // We will explore further
+      ans |= EXPLORE(board, i, j + 1, m, n, wordCharIndex + 1, word, taken);
+      ans |= EXPLORE(board, i, j - 1, m, n, wordCharIndex + 1, word, taken);
+      ans |= EXPLORE(board, i + 1, j, m, n, wordCharIndex + 1, word, taken);
+      ans |= EXPLORE(board, i - 1, j, m, n, wordCharIndex + 1, word, taken);
+    }
+    taken[i][j] = false;
+    return ans;
+  }
+
+  public static void main(String[] args) {
+    char[][] board = {{'A', 'B', 'C', 'E'}, {'S', 'F', 'C', 'S'}, {'A', 'D', 'E', 'E'}};
+    System.out.println(new WordSearch().exist(board, "ABCCED"));
+    System.out.println(new WordSearch().exist(board, "ABCF"));
+    System.out.println(new WordSearch().exist(board, "SEE"));
+  }
+}