规范格式

leetcode/0210.Course-Schedule-II/210. Course Schedule II.go

@@ -0,0 +1,30 @@
+package leetcode
+
+func findOrder(numCourses int, prerequisites [][]int) []int {
+	in := make([]int, numCourses)
+	frees := make([][]int, numCourses)
+	next := make([]int, 0, numCourses)
+	for _, v := range prerequisites {
+		in[v[0]]++
+		frees[v[1]] = append(frees[v[1]], v[0])
+	}
+	for i := 0; i < numCourses; i++ {
+		if in[i] == 0 {
+			next = append(next, i)
+		}
+	}
+	for i := 0; i != len(next); i++ {
+		c := next[i]
+		v := frees[c]
+		for _, vv := range v {
+			in[vv]--
+			if in[vv] == 0 {
+				next = append(next, vv)
+			}
+		}
+	}
+	if len(next) == numCourses {
+		return next
+	}
+	return []int{}
+}

leetcode/0210.Course-Schedule-II/210. Course Schedule II_test.go

@@ -0,0 +1,58 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question210 struct {
+	para210
+	ans210
+}
+
+// para 是参数
+// one 代表第一个参数
+type para210 struct {
+	one int
+	pre [][]int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans210 struct {
+	one []int
+}
+
+func Test_Problem210(t *testing.T) {
+
+	qs := []question210{
+
+		question210{
+			para210{2, [][]int{[]int{1, 0}}},
+			ans210{[]int{0, 1}},
+		},
+
+		question210{
+			para210{2, [][]int{[]int{1, 0}, []int{0, 1}}},
+			ans210{[]int{0, 1, 2, 3}},
+		},
+
+		question210{
+			para210{4, [][]int{[]int{1, 0}, []int{2, 0}, []int{3, 1}, []int{3, 2}}},
+			ans210{[]int{0, 1, 2, 3}},
+		},
+
+		question210{
+			para210{3, [][]int{[]int{1, 0}, []int{1, 2}, []int{0, 1}}},
+			ans210{[]int{}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 210------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans210, q.para210
+		fmt.Printf("【input】:%v       【output】:%v\n", p, findOrder(p.one, p.pre))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0210.Course-Schedule-II/README.md

@@ -0,0 +1,42 @@
+# [210. Course Schedule II](https://leetcode.com/problems/course-schedule-ii/)
+
+
+## 题目
+
+There are a total of *n* courses you have to take, labeled from `0` to `n-1`.
+
+Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: `[0,1]`
+
+Given the total number of courses and a list of prerequisite **pairs**, return the ordering of courses you should take to finish all courses.
+
+There may be multiple correct orders, you just need to return one of them. If it is impossible to finish all courses, return an empty array.
+
+**Example 1:**
+
+    Input: 2, [[1,0]] 
+    Output: [0,1]
+    Explanation: There are a total of 2 courses to take. To take course 1 you should have finished   
+                 course 0. So the correct course order is [0,1] .
+
+**Example 2:**
+
+    Input: 4, [[1,0],[2,0],[3,1],[3,2]]
+    Output: [0,1,2,3] or [0,2,1,3]
+    Explanation: There are a total of 4 courses to take. To take course 3 you should have finished both     
+                 courses 1 and 2. Both courses 1 and 2 should be taken after you finished course 0. 
+                 So one correct course order is [0,1,2,3]. Another correct ordering is [0,2,1,3] .
+
+**Note:**
+
+1. The input prerequisites is a graph represented by **a list of edges**, not adjacency matrices. Read more about [how a graph is represented](https://www.khanacademy.org/computing/computer-science/algorithms/graph-representation/a/representing-graphs).
+2. You may assume that there are no duplicate edges in the input prerequisites.
+
+## 题目大意
+
+现在你总共有 n 门课需要选，记为 0 到 n-1。在选修某些课程之前需要一些先修课程。 例如，想要学习课程 0 ，你需要先完成课程 1 ，我们用一个匹配来表示他们: [0,1]。给定课程总量以及它们的先决条件，返回你为了学完所有课程所安排的学习顺序。可能会有多个正确的顺序，你只要返回一种就可以了。如果不可能完成所有课程，返回一个空数组。
+
+
+## 解题思路
+
+- 给出 n 个任务，每两个任务之间有相互依赖关系，比如 A 任务一定要在 B 任务之前完成才行。问是否可以完成所有任务，如果可以完成任务，就输出完成任务的顺序，如果不能完成，输出空数组。
+- 这一题是第 207 题的加强版。解题思路是 AOV 网的拓扑排序。最后输出数组即可。代码和第 207 题基本不变。具体解题思路见第 207 题。