1460.Class ScheduleIV

topic：

[1460]Class ScheduleIV.md

Thought：

一开始的想法是构建有向picture，然后在有向picture中找到queryDoes the two points have a father -son relationship?。
But watchylbAfter the answer，I find that the accessability is faster first。
First traversalprerequirements，Record all the accessibility。
Then triple cycle，Connect all the availability。

i->j->k，ifi->k，Soi->kIt is。

Code：

class Solution:
    def checkIfPrerequisite(self, n: int, prerequisites: List[List[int]], queries: List[List[int]]) -> List[
        bool]:
        f = [[False] * n for _ in range(n)]
        for a, b in prerequisites:
            f[a][b] = True
        for k in range(n):
            for i in range(n):
                for j in range(n):
                    f[i][j] = f[i][j] or (f[i][k] and f[k][j])
        return [f[a][b] for a, b in queries]