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src/main/java/com/dota/gridGraph/_1765/Solution.java

@@ -0,0 +1,37 @@
+package com.dota.gridGraph._1765;
+
+import java.util.ArrayDeque;
+
+class Solution {
+	public int[][] highestPeak(int[][] isWater) {
+		int n = isWater.length;
+		int m = isWater[0].length;
+		var queue = new ArrayDeque<int[]>();
+		var book = new boolean[n][m];
+		for (int i = 0; i < n; i++) {
+			for (int j = 0; j < m; j++) {
+				if (isWater[i][j] == 1) {
+					queue.add(new int[]{i, j});
+					isWater[i][j] = 0;
+					book[i][j] = true;
+				}
+			}
+		}
+		var next = new int[][]{{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
+		while (!queue.isEmpty()) {
+			var xy = queue.poll();
+			int x = xy[0];
+			int y = xy[1];
+			for (int[] ints : next) {
+				int nextX = x + ints[0];
+				int nextY = y + ints[1];
+				if (nextX < 0 || nextY < 0 || nextX >= n || nextY >= m || book[nextX][nextY]) continue;
+				isWater[nextX][nextY] = isWater[x][y] + 1;
+				book[nextX][nextY] = true;
+				queue.offer(new int[]{nextX, nextY});
+			}
+		}
+
+		return isWater;
+	}
+}

src/main/java/com/dota/gridGraph/_827/Solution.java

@@ -0,0 +1,77 @@
+package com.dota.gridGraph._827;
+
+import java.util.HashMap;
+import java.util.HashSet;
+
+class Solution {
+	public int largestIsland(int[][] grid) {
+		int res = 0;
+		var map = new HashMap<Integer, Integer>();
+		var idx = 2;
+		for (int i = 0; i < grid.length; i++) {
+			for (int j = 0; j < grid[0].length; j++) {
+				if (grid[i][j] == 1) {
+					goin(i, j, grid, idx, map);
+					idx++;
+				}
+			}
+		}
+
+		for (int i = 0; i < grid.length; i++) {
+			for (int j = 0; j < grid[0].length; j++) {
+				if (grid[i][j] == 0) {
+					int sum = df(i, j, grid, map);
+					res = Math.max(res, sum);
+				}
+			}
+		}
+		int n = grid.length;
+		return res==0?n*n:res;
+	}
+
+	void goin(int i, int j, int[][] grid, int idx, HashMap<Integer, Integer> map) {
+		if (i < 0 || j < 0 || i >= grid.length || j >= grid[0].length || grid[i][j] != 1) return;
+		grid[i][j] = idx;
+		map.merge(idx, 1, Integer::sum);
+		goin(i - 1, j, grid, idx, map);
+		goin(i + 1, j, grid, idx, map);
+		goin(i, j - 1, grid, idx, map);
+		goin(i, j + 1, grid, idx, map);
+	}
+
+	int df(int i, int j, int[][] grid, HashMap<Integer, Integer> map) {
+		var set = new HashSet<Integer>();
+		int sum = 1;
+		int t = dfs(i - 1, j, grid, map);
+		if (t > 0) {
+			sum += t;
+			set.add(grid[i - 1][j]);
+		}
+
+		t = dfs(i + 1, j, grid, map);
+		if (t > 0 && !set.contains(grid[i + 1][j])) {
+			sum += t;
+			set.add(grid[i + 1][j]);
+		}
+
+		t = dfs(i, j - 1, grid, map);
+		if (t > 0 && !set.contains(grid[i][j - 1])) {
+			sum += t;
+			set.add(grid[i][j - 1]);
+		}
+		t = dfs(i, j + 1, grid, map);
+		if (t > 0 && !set.contains(grid[i][j + 1])) {
+			sum += t;
+			set.add(grid[i][j + 1]);
+		}
+		return sum;
+	}
+
+	int dfs(int i, int j, int[][] grid, HashMap<Integer, Integer> map) {
+		if (i < 0 || j < 0 || i >= grid.length || j >= grid[0].length || grid[i][j] == 0) {
+			return 0;
+		}
+
+		return map.get(grid[i][j]);
+	}
+}