heozeop: word search

Author: heozeop

word-search/heozeop.cpp

@@ -0,0 +1,63 @@
+// time complexity: O(n * m * 3 ^ L), L은 최대 깊이
+// spatial complexity: O((n * m ) ^ 2)
+
+class Solution {
+public:
+  bool exist(vector<vector<char>>& board, string word) {
+    vector<vector<bool>> visit;
+    for(int i = 0; i < board.size(); ++i) {
+      for(int j = 0; j < board[0].size(); ++j) {
+        if(board[i][j] != word[0]) continue;
+        visit = vector(board.size(), vector(board[0].size(), false));
+        visit[i][j] = true;
+        if (find(board, word, 1, {i,j}, visit)) {
+          return true;
+        }
+      }
+    }
+
+    return false;
+  }
+
+  bool find(
+    vector<vector<char>>& board, 
+    string word, 
+    int fi, 
+    pair<int,int> curPos, 
+    vector<vector<bool>>& visit
+  ) {
+    if(fi == word.length()) {
+      return true;
+    }
+
+    char target = word[fi];
+    int nr,ny;
+    for(int i = 0; i < 4; ++i) {
+      nr = curPos.first + DIRECTIONS[i][0];
+      ny = curPos.second+ DIRECTIONS[i][1];
+
+      if (isOutSideOfBoard({nr,ny}, {board.size(), board[0].size()}) || visit[nr][ny] || board[nr][ny] != target) {
+        continue;
+      }
+
+      visit[nr][ny] = true;
+      if(find(board, word, fi + 1, {nr,ny}, visit)) {
+        return true;
+      }
+      visit[nr][ny] = false;
+    }
+
+    return false;
+  }
+
+  int DIRECTIONS[4][2] = {
+    {-1, 0},
+    {0, 1},
+    {1, 0},
+    {0, -1},
+  };
+
+  bool isOutSideOfBoard(pair<int,int> cur, pair<int,int> boardSize) {
+    return cur.first < 0 || cur.second < 0 || cur.first >= boardSize.first || cur.second >= boardSize.second;
+  }
+};