From 1ce5b20640f8b5436ea023424a9d1263792d4ff5 Mon Sep 17 00:00:00 2001
From: ashmichheda <ashmichheda@gmail.com>
Date: Sun, 24 Jan 2021 18:41:19 -0700
Subject: [PATCH] added solution and test case for 79

---
 .../java/com/fishercoder/solutions/_79.java   | 41 +++++++++++++++++++
 src/test/java/com/fishercoder/_79Test.java    | 13 ++++++
 2 files changed, 54 insertions(+)

diff --git a/src/main/java/com/fishercoder/solutions/_79.java b/src/main/java/com/fishercoder/solutions/_79.java
index 52708b13cd..36dec569f4 100644
--- a/src/main/java/com/fishercoder/solutions/_79.java
+++ b/src/main/java/com/fishercoder/solutions/_79.java
@@ -40,4 +40,45 @@ boolean search(char[][] board, String word, int i, int j, int pos) {
             return false;
         }
     }
+
+    // O(1) space solution
+    public static class Solution2 {
+        public boolean exist(char[][] board, String word) {
+
+            // do DFS traversal
+            int row = board.length;
+            int col = board[0].length;
+
+            for (int i = 0; i < row; i++) {
+                for (int j = 0; j < col; j++) {
+                    if (board[i][j] == word.charAt(0) && search(board, i, j, word, 0) == true)
+                        return true;
+                }
+            }
+            return false;
+        }
+
+        private boolean search(char[][] board, int i, int j, String word, int index) {
+            if (index == word.length() - 1)
+                return true;
+
+            // store the visited char in temp variable
+            char temp = board[i][j];
+            board[i][j] = ' ';
+            if (i > 0 && board[i - 1][j] == word.charAt(index + 1) && search(board, i - 1, j, word, index + 1) == true)
+                return true;
+            if (i < board.length - 1 && board[i + 1][j] == word.charAt(index + 1) && search(board, i + 1, j, word, index + 1) == true)
+                return true;
+
+            if (j > 0 && board[i][j - 1] == word.charAt(index + 1) && search(board, i, j - 1, word, index + 1) == true)
+                return true;
+
+
+            if (j < board[0].length - 1 && board[i][j + 1] == word.charAt(index + 1) && search(board, i, j + 1, word, index + 1) == true)
+                return true;
+
+            board[i][j] = temp;
+            return false;
+        }
+    }
 }
diff --git a/src/test/java/com/fishercoder/_79Test.java b/src/test/java/com/fishercoder/_79Test.java
index c9c20c3ac1..3cd764d535 100644
--- a/src/test/java/com/fishercoder/_79Test.java
+++ b/src/test/java/com/fishercoder/_79Test.java
@@ -8,11 +8,14 @@
 
 public class _79Test {
     private static _79.Solution1 solution1;
+    private static _79.Solution2 solution2;
     private static char[][] board;
 
     @BeforeClass
     public static void setup() {
+
         solution1 = new _79.Solution1();
+        solution2 = new _79.Solution2();
     }
 
     @Test
@@ -48,4 +51,14 @@ public void test3() {
         assertEquals(false, solution1.exist(board, "aaa"));
     }
 
+    @Test
+    public void test4() {
+        board = new char[][]{
+                {'A', 'B', 'H', 'I'},
+                {'K', 'E', 'H', 'S'},
+                {'A', 'D', 'E', 'E'},
+        };
+        assertEquals(true, solution2.exist(board, "ABHISHEK"));
+    }
+
 }