How to Solve Count All Valid Pickup and Delivery Options Problem
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Count All Valid Pickup and Delivery Options
Given n orders, each order consists of a pickup and a delivery service. Count all valid pickup/delivery possible sequences such that delivery(i) is always after of pickup(i). Since the answer may be t...
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Understanding the Count All Valid Pickup and Delivery Options Problem
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Problem Statement
Given n orders, each order consists of a pickup and a delivery service. Count all valid pickup/delivery possible sequences such that delivery(i) is always after of pickup(i). Since the answer may be too large, return it modulo 10^9 + 7.
Count All Valid Pickup and Delivery Options
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Examples
n = 11Unique order (P1, D1), Delivery 1 always is after of Pickup 1.
n = 26All possible orders: (P1,P2,D1,D2), (P1,P2,D2,D1), (P1,D1,P2,D2), (P2,P1,D1,D2), (P2,P1,D2,D1) and (P2,D2,P1,D1). This is an invalid order (P1,D2,P2,D1) because Pickup 2 is after of Delivery 2.
n = 390Constraints
1 <= n <= 500How Interview Coder Helps with Leetcode Problems
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