From cdc5a1e9e47690fee5c5f5b34d66f643d6e08907 Mon Sep 17 00:00:00 2001
From: Terry Liu <102352821+Lozakaka@users.noreply.github.com>
Date: Mon, 26 Jun 2023 21:37:58 -0400
Subject: [PATCH] =?UTF-8?q?=E6=96=B0=E5=A2=9EJAVA=E8=A7=A3=E6=B3=95?=
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1. java的BFS解法有寫一個helper function去呼叫
2. java's DFS with 終止條件
---
 problems/0130.被围绕的区域.md | 89 +++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/problems/0130.被围绕的区域.md b/problems/0130.被围绕的区域.md
index abb68e19..e244873b 100644
--- a/problems/0130.被围绕的区域.md
+++ b/problems/0130.被围绕的区域.md
@@ -188,6 +188,54 @@ class Solution {
     }
 }
 ```
+```Java
+//BFS（使用helper function）
+class Solution {
+    int[][] dir ={{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
+    public void solve(char[][] board) {
+        for(int i = 0; i < board.length; i++){
+            if(board[i][0] == 'O') bfs(board, i, 0);
+            if(board[i][board[0].length - 1] == 'O') bfs(board, i, board[0].length - 1);
+        }
+
+        for(int j = 1 ; j < board[0].length - 1; j++){
+            if(board[0][j] == 'O') bfs(board, 0, j);
+            if(board[board.length - 1][j] == 'O') bfs(board, board.length - 1, j);
+        }
+
+        for(int i = 0; i < board.length; i++){
+            for(int j = 0; j < board[0].length; j++){
+                if(board[i][j] == 'O') board[i][j] = 'X';
+                if(board[i][j] == 'A') board[i][j] = 'O';
+            }
+        }
+    }
+    private void bfs(char[][] board, int x, int y){
+        Queue<Integer> que = new LinkedList<>();
+        board[x][y] = 'A';
+        que.offer(x);
+        que.offer(y);
+        
+        while(!que.isEmpty()){
+            int currX = que.poll();
+            int currY = que.poll();
+
+            for(int i = 0; i < 4; i++){
+                int nextX = currX + dir[i][0];
+                int nextY = currY + dir[i][1];
+
+            if(nextX < 0 || nextY < 0 || nextX >= board.length || nextY >= board[0].length)
+                continue;
+            if(board[nextX][nextY] == 'X'|| board[nextX][nextY] == 'A')
+                continue;
+            bfs(board, nextX, nextY);
+            }
+        }
+    }
+}
+
+```
+
 ```Java
 // 深度优先遍历
 // 使用 visited 数组进行标记
@@ -296,6 +344,47 @@ class Solution {
     }
 }
 ```
+```java
+//DFS(有終止條件)
+class Solution {
+    int[][] dir ={{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
+    public void solve(char[][] board) {
+
+        for(int i = 0; i < board.length; i++){
+            if(board[i][0] == 'O') dfs(board, i, 0);
+            if(board[i][board[0].length - 1] == 'O') dfs(board, i, board[0].length - 1);
+        }
+
+        for(int j = 1 ; j < board[0].length - 1; j++){
+            if(board[0][j] == 'O') dfs(board, 0, j);
+            if(board[board.length - 1][j] == 'O') dfs(board, board.length - 1, j);
+        }
+
+        for(int i = 0; i < board.length; i++){
+            for(int j = 0; j < board[0].length; j++){
+                if(board[i][j] == 'O') board[i][j] = 'X';
+                if(board[i][j] == 'A') board[i][j] = 'O';
+            }
+        }        
+    }
+
+    private void dfs(char[][] board, int x, int y){
+        if(board[x][y] == 'X'|| board[x][y] == 'A')
+            return;
+        board[x][y] = 'A';
+        for(int i = 0; i < 4; i++){
+            int nextX = x + dir[i][0];
+            int nextY = y + dir[i][1];
+            
+            if(nextX < 0 || nextY < 0 || nextX >= board.length || nextY >= board[0].length)
+                continue;
+            // if(board[nextX][nextY] == 'X'|| board[nextX][nextY] == 'A')
+            //     continue;
+            dfs(board, nextX, nextY);
+        }
+    }
+}
+```
 
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