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src/main/java/com/dota/gridGraph/_417/Solution.java

@@ -0,0 +1,53 @@
+package com.dota.gridGraph._417;
+
+import java.util.ArrayList;
+import java.util.List;
+
+class Solution {
+	boolean a = false, b = false;
+
+	public List<List<Integer>> pacificAtlantic(int[][] heights) {
+		var book = new boolean[heights.length][heights[0].length];
+		for (int i = 0; i < book.length; i++) {
+			book[i] = new boolean[heights[0].length];
+		}
+		var res = new ArrayList<List<Integer>>();
+		for (int i = 0; i < heights.length; i++) {
+			for (int j = 0; j < heights[i].length; j++) {
+				a = false;
+				b = false;
+				dfs(i, j, heights, book, heights[i][j]);
+				if (a&&b) {
+					res.add(List.of(i,j));
+				}
+			}
+		}
+		return res;
+	}
+
+	void dfs(int i, int j, int[][] heights, boolean[][] book, int last) {
+		if (a && b) return;
+		if (i < 0 || j < 0) {
+			a = true;
+			return;
+		}
+		if (i >= heights.length || j >= heights[0].length) {
+			b = true;
+			return;
+		}
+
+		if (book[i][j]) {
+			return;
+		}
+		if (heights[i][j] > last) {
+			return;
+		}
+
+		book[i][j] = true;
+		dfs(i + 1, j, heights, book, heights[i][j]);
+		dfs(i - 1, j, heights, book, heights[i][j]);
+		dfs(i, j + 1, heights, book, heights[i][j]);
+		dfs(i, j - 1, heights, book, heights[i][j]);
+		book[i][j] = false;
+	}
+}