Solve 210 with C++

Author: illuz

solutions/210.Course_Schedule_II/AC_dfs_n.cpp

@@ -0,0 +1,68 @@
+/*
+*  Author:      illuz <iilluzen[at]gmail.com>
+*  File:        AC_dfs_n.cpp
+*  Create Date: 2016-02-27 12:00:45
+*  Descripton:   
+*/
+
+#include <bits/stdc++.h>
+
+using namespace std;
+const int N = 0;
+
+class Solution {
+public:
+    vector<int> findOrder(int numCourses, vector<pair<int, int>>& prerequisites) {
+        graph = vector<vector<int> >(numCourses);
+        vis = vector<int>(numCourses);
+
+        vector<int> inorder(numCourses);
+        vector<int> path;
+        // generate the tree map
+        for (auto prerequisite : prerequisites) {
+            graph[prerequisite.second].push_back(prerequisite.first);
+            inorder[prerequisite.first] += 1;
+        }
+        // find out 0-in-order node and dfs
+        for (int i = 0; i < numCourses; ++i) {
+            if (inorder[i] == 0) {
+                if (dfs(i, path) == false) // can not topsort
+                    return vector<int>();
+            }
+        }
+        if (path.size() != numCourses)
+            return vector<int>();
+        reverse(path.begin(), path.end());
+        return path;
+    }
+private:
+    vector<vector<int> > graph;
+    vector<int> vis;
+
+    bool dfs(int id, vector<int> &path) {
+        vis[id] = 1; // visiting
+        for (auto toid : graph[id]) {
+            if (vis[toid] == 1)
+                return false;
+            if (vis[toid] == 2)
+                continue;
+            if (dfs(toid, path) == false)
+                return false;
+        }
+        vis[id] = 2; // visited
+        path.push_back(id);
+        return true;
+    }
+};
+
+int main() {
+    Solution s;
+    vector<pair<int, int>> prerequisites;
+    prerequisites.push_back(pair<int, int>(0, 2));
+    prerequisites.push_back(pair<int, int>(2, 0));
+    prerequisites.push_back(pair<int, int>(1, 2));
+    vector<int> res = s.findOrder(3, prerequisites);
+    for (auto x : res) cout << x << ' ';
+    return 0;
+}
+