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src/main/java/com/dota/graph/_2316/Solution.java

@@ -0,0 +1,39 @@
+package com.dota.graph._2316;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+class Solution {
+	public long countPairs(int n, int[][] edges) {
+		List<Integer>[] g = new ArrayList[n];
+		Arrays.setAll(g, i -> new ArrayList<>());
+		for (int[] edge : edges) {
+			g[edge[0]].add(edge[1]);
+			g[edge[1]].add(edge[0]);
+		}
+
+		var vis = new boolean[n];
+		long res = 0;
+		int sum = 0;
+		for (int i = 0; i < g.length; i++) {
+			if (!vis[i]) {
+				int size = dfs(i, vis, g);
+				res += (long)size * sum;
+				sum += size;
+			}
+		}
+		return res;
+	}
+
+	int dfs(int i, boolean[] visited, List<Integer>[] arr) {
+		visited[i] = true;
+		int size = 1;
+		for (Integer integer : arr[i]) {
+			if (!visited[integer]) {
+				size += dfs(integer, visited, arr);
+			}
+		}
+		return size;
+	}
+}

src/main/java/com/dota/gridGraph/_1559/Solution.java

@@ -0,0 +1,37 @@
+package com.dota.gridGraph._1559;
+
+class Solution {
+	public boolean containsCycle(char[][] grid) {
+		int n = grid.length;
+		int m = grid[0].length;
+		var book = new int[n][m];
+		for (int i = 0; i < n; i++) {
+			for (int j = 0; j < m; j++) {
+				if (book[i][j] == 0) {
+					var res = df(i, j, i, j, grid[i][j], book, 0, grid);
+					if (res) {
+						return true;
+					}
+				}
+			}
+		}
+		return false;
+	}
+
+	boolean df(int i, int j, int x, int y, char c, int[][] book, int step, char[][] chars) {
+		if (i < 0 || j < 0 || i >= book.length || j >= book[i].length || c != chars[i][j]) {
+			return false;
+		}
+
+		if (book[i][j] == 0) {
+			step++;
+			book[i][j] = step;
+			return df(i + 1, j, i, j, c, book, step, chars) ||
+					df(i - 1, j, i, j, c, book, step, chars) ||
+					df(i, j + 1, i, j, c, book, step, chars) ||
+					df(i, j - 1, i, j, c, book, step, chars);
+		}
+
+		return book[x][y] - book[i][j] > 2;
+	}
+}