[Week4](gmlwls96) word search

Author: gmlwls96

word-search/gmlwls96.kt

@@ -0,0 +1,67 @@
+class Solution {
+
+    // 풀이 : dfs
+    // 시간 :O(m * n * 4^w), 공간 :O(m * n + w)
+    val movePos = arrayOf(
+        intArrayOf(-1, 0),
+        intArrayOf(0, -1),
+        intArrayOf(1, 0),
+        intArrayOf(0, 1)
+    )
+
+    fun exist(board: Array<CharArray>, word: String): Boolean {
+        for (y in board.indices) {
+            for (x in board[y].indices) {
+                if (existDfs(
+                        board,
+                        Array(board.size) { BooleanArray(board[it].size) },
+                        word,
+                        "",
+                        y,
+                        x
+                    )
+                ) {
+                    return true
+                }
+            }
+        }
+        return false
+    }
+
+    private fun existDfs(
+        board: Array<CharArray>,
+        visit: Array<BooleanArray>,
+        findWord: String,
+        currentWord: String,
+        y: Int,
+        x: Int
+    ): Boolean {
+        if (findWord == currentWord) return true
+        val findChar = findWord[currentWord.length]
+        if (board[y][x] == findChar) {
+            val newWord = currentWord + board[y][x]
+            visit[y][x] = true
+            for (pos in movePos) {
+                val newY = y + pos[0]
+                val newX = x + pos[1]
+                if (newY >= 0 && newX >= 0
+                    && newY < board.size
+                    && newX < board[newY].size
+                    && !visit[newY][newX]
+                    && existDfs(
+                        board = board,
+                        visit = visit,
+                        findWord = findWord,
+                        currentWord = newWord,
+                        y = newY,
+                        x = newX
+                    )
+                ) {
+                    return true
+                }
+            }
+            visit[y][x] = false
+        }
+        return false
+    }
+}