README.md

754. Reach a Number

You are standing at position 0 on an infinite number line. There is a goal at position target.

On each move, you can either go left or right. During the n-th move (starting from 1), you take n steps.

Return the minimum number of steps required to reach the destination.

Example 1:

Input: target = 3
Output: 2
Explanation:
On the first move we step from 0 to 1.
On the second step we step from 1 to 3.

Example 2:

Input: target = 2
Output: 3
Explanation:
On the first move we step from 0 to 1.
On the second move we step  from 1 to -1.
On the third move we step from -1 to 2.

Note:

• target will be a non-zero integer in the range [-109, 109].

Solutions (Rust)

1. Mathematical

impl Solution {
    pub fn reach_number(target: i32) -> i32 {
        let mut target = target;
        let mut position = 0;
        let mut step = 0;
        if target < 0 {
            target = -target;
        }
        while position < target {
            step += 1;
            position += step;
        }
        if (position - target) % 2 == 0 {
            step
        } else if step % 2 == 0 {
            step + 1
        } else {
            step + 2
        }
    }
}