题目：

题解：

func findOrder(numCourses int, prerequisites [][]int) []int {
    var (
        edges = make([][]int, numCourses)
        indeg = make([]int, numCourses)
        result []int
    )

    for _, info := range prerequisites {
        edges[info[1]] = append(edges[info[1]], info[0])
        indeg[info[0]]++
    }

    q := []int{}
    for i := 0; i < numCourses; i++ {
        if indeg[i] == 0 {
            q = append(q, i)
        }
    }

    for len(q) > 0 {
        u := q[0]
        q = q[1:]
        result = append(result, u)
        for _, v := range edges[u] {
            indeg[v]--
            if indeg[v] == 0 {
                q = append(q, v)
            }
        }
    }
    if len(result) != numCourses {
        return []int{}
    }
    return result
}