**Number of Ways to Reach a Position After Exactly k Steps solution leetcode **– You are given two **positive** integers `startPos`

and `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**

`10`^{9} + 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 = 3Output:3Explanation: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 = 10Output:0Explanation:It is impossible to reach position 5 from position 2 in exactly 10 steps.

**Constraints:**

`1 <= startPos, endPos, k <= 1000`