547. Number of Provinces

Author: zhaoguanchen

README.md

@@ -129,6 +129,7 @@ The project is divided into two parts: `structure` and `solution`.
 | No.  | Title                                                        | Difficulty | Solution                                                     | Idea       |
 | ---- | ------------------------------------------------------------ | ---------- | ------------------------------------------------------------ | ---------- |
 | 329  | [Longest Increasing Path in a Matrix](https://leetcode.com/problems/longest-increasing-path-in-a-matrix/) | Hard       | [LongestIncreasingPathInAMatrix.java](src/leetcode/solution/DFS/LongestIncreasingPathInAMatrix.java) | DFS + Memo |
+| 547  | [Number of Provinces](https://leetcode.com/problems/number-of-provinces/) | Medium     | [NumberOfProvinces.java](src/leetcode/solution/DFS/NumberOfProvinces.java) | DFS        |
 | 802  | [Find Eventual Safe States](https://leetcode.com/problems/find-eventual-safe-states/) | Hard       | [LongestIncreasingPathInAMatrix.java](src/leetcode/solution/DFS/LongestIncreasingPathInAMatrix.java) | DFS + Memo |
 | 2267 | [Check if There Is a Valid Parentheses String Path](https://leetcode.com/problems/check-if-there-is-a-valid-parentheses-string-path/) | Medium     | [FindEventualSafeStates.java](src/leetcode/solution/DFS/FindEventualSafeStates.java) | DFS        |
 

src/leetcode/solution/DFS/NumberOfProvinces.java

@@ -0,0 +1,60 @@
+package leetcode.solution.DFS;
+
+/**
+ * 547. Number of Provinces
+ */
+public class NumberOfProvinces {
+
+    public static void main(String[] args) {
+        int[][] grid = {{1, 1, 0}, {1, 1, 0}, {0, 0, 1}};
+        NumberOfProvinces numberOfProvinces = new NumberOfProvinces();
+        int ans = numberOfProvinces.findCircleNum(grid);
+        System.out.println(ans);
+        // 2
+    }
+
+    int[][] isConnected;
+
+    int[] visited;
+
+    int n;
+
+    public int findCircleNum(int[][] isConnected) {
+        this.n = isConnected.length;
+        this.isConnected = isConnected;
+        this.visited = new int[n];
+
+        int count = 0;
+        for (int i = 0; i < n; i++) {
+            if (visited[i] == 1) {
+                continue;
+            }
+            dfs(i);
+            count++;
+        }
+
+        return count;
+
+    }
+
+    private void dfs(int city) {
+        visited[city] = 1;
+
+        for (int i = 0; i < n; i++) {
+            if (city == i) {
+                continue;
+            }
+
+            if (isConnected[city][i] == 0) {
+                continue;
+            }
+
+            if (visited[i] == 1) {
+                continue;
+            }
+
+            dfs(i);
+        }
+
+    }
+}