An onboarding flow has n screens numbered 0 to n - 1. Each pair [from, to] in links is a button on screen from that opens screen to. Links never lead back to an earlier point of a flow, so there are no cycles, and no link appears twice.
Write countFlowPaths(n, links) that returns how many different paths lead from screen 0 to screen n - 1. If n is 1, the start is already the end, which counts as one path.
The count can be very large, so return it modulo 1000000007.
Input: n = 4, links = [[0,1],[0,2],[1,3],[2,3]] Output: 2
0 → 1 → 3 and 0 → 2 → 3.
Input: n = 5, links = [[0,1],[1,2],[0,2],[2,4],[2,3],[3,4]] Output: 4
Two ways to reach screen 2, then two ways from 2 to 4.
1 <= n <= 20000 <= links.length <= 10000Run tries your code on the examples. Submit runs every test, including hidden edge cases, and solves the problem when they all pass.
Ctrl + Enter runs, Ctrl + Shift + Enter submits (⌘ on a Mac).
I'm here to help with #489 Onboarding Flow Path Count. I give hints, never the solution, so you get to solve it yourself. Ask for a hint, select code to ask about it, or press Ask Tuto why on a failing test.
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