[Graph] programmers 순위

Author: Seogeurim

README.md

@@ -286,6 +286,7 @@
 | 08  |     | [Baekjoon-21276 계보 복원가 호석](./src/Graph/P21276)      | [위상정렬](./notes/Graph/TopologicalSort.md) |
 | 09  | ⭐️  | [Baekjoon-2458 키 순서](./src/Graph/P2458)               |                  |
 | 10  |     | [Programmers 가장 먼 노드](./src/Graph/prg49189)          |      |
+| 11  |     | [Programmers 순위](./src/Graph/prg49191)                |      |
 
 ### Minimum Spanning Tree (MST)
 

src/Graph/prg49191/README.md

@@ -0,0 +1,7 @@
+## [programmers - 그래프] 순위
+
+![image](https://user-images.githubusercontent.com/22045163/116101038-77f37700-a6e8-11eb-91c3-02a1bb84052c.png)
+
+### 유사한 문제
+
+[BOJ 2458 키 순서](../P2458) 문제와 비슷하며 풀이도 동일하게 해서 풀었다.

src/Graph/prg49191/Solution.java

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+package Graph.prg49191;
+
+class Solution {
+
+    int[][] graph;
+
+    public int solution(int n, int[][] results) {
+
+        graph = new int[n+1][n+1];
+        for (int[] res : results) {
+            graph[res[0]][res[1]] = 1;
+        } // graph[A][B] == 1 : A는 B를 이겼다.
+
+        for (int i = 1; i <= n; i++) {
+            graph[i][0] = -1;
+        }
+
+        for (int i = 1; i <= n; i++) {
+            dfs(i, n);
+        }
+
+        for (int i = 1; i <= n; i++) {
+            for (int j = 1; j <= n; j++) {
+                graph[0][j] += graph[i][j];
+            }
+        }
+
+        int ans = 0;
+        for (int i = 1; i <= n; i++) {
+            if (graph[0][i] + graph[i][0] == n-1) ans ++;
+        }
+
+        return ans;
+    }
+
+    void dfs(int cur, int n) {
+
+        for (int i = 1; i <= n; i++) {
+            if (graph[cur][i] == 1) {
+                if (graph[i][0] == -1) dfs(i, n);
+                for (int j = 1; j <= n; j++) {
+                    if (graph[i][j] == 1) graph[cur][j] = 1;
+                }
+            }
+        }
+
+        int cnt = 0;
+        for (int i = 1; i <= n; i++) {
+            cnt += graph[cur][i];
+        }
+        graph[cur][0] = cnt;
+    }
+}