Number of Ways to Reach a Position After Exactly k Steps solution leetcode – You are given two positive integers
endPos. Initially, you are standing at position
startPos on an infinite number line. With one step, you can move either one position to the left, or one position to the right.
Number of Ways to Reach a Position After Exactly k Steps solution leetcode
Given a positive integer
k, return the number of different ways to reach the position
endPos starting from
startPos, such that you perform exactly
k steps. Since the answer may be very large, return it modulo
109 + 7.
Two ways are considered different if the order of the steps made is not exactly the same.
Note that the number line includes negative integers.
Example 1: Number of Ways to Reach a Position After Exactly k Steps solution leetcode
Input: startPos = 1, endPos = 2, k = 3 Output: 3 Explanation: We can reach position 2 from 1 in exactly 3 steps in three ways: - 1 -> 2 -> 3 -> 2. - 1 -> 2 -> 1 -> 2. - 1 -> 0 -> 1 -> 2. It can be proven that no other way is possible, so we return 3.
Example 2: Number of Ways to Reach a Position After Exactly k Steps solution leetcode
Input: startPos = 2, endPos = 5, k = 10 Output: 0 Explanation: It is impossible to reach position 5 from position 2 in exactly 10 steps.
1 <= startPos, endPos, k <= 1000