add new solutions

solutions/2/q210/solution.go

@@ -0,0 +1,34 @@
+package q210
+
+func findOrder(numCourses int, prerequisites [][]int) []int {
+	ndeps := make([]int, numCourses)
+	revDeps := make([][]int, numCourses)
+	ret := make([]int, 0, numCourses)
+
+	for i := range prerequisites {
+		c, dep := prerequisites[i][0], prerequisites[i][1]
+		ndeps[c]++
+		revDeps[dep] = append(revDeps[dep], c)
+	}
+
+	for i := range ndeps {
+		if ndeps[i] == 0 {
+			ret = append(ret, i)
+		}
+	}
+	for i := 0; i < len(ret); i++ {
+		for _, c := range revDeps[ret[i]] {
+			ndeps[c]--
+			if ndeps[c] == 0 {
+				ret = append(ret, c)
+			}
+		}
+	}
+
+	if len(ret) != numCourses {
+		return nil
+	}
+	return ret
+}
+
+var _ = findOrder