Broken calculator

Math Greedy

55.9% acceptance

Feb 25, 2026

2836

216

There is a broken calculator that has the integer startValue on its display initially. In one operation, you can: multiply the number on display by 2, or subtract 1 from the number on display. Given two integers startValue and target, return the minimum number of operations needed to display target on the calculator.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn broken_calc(start_value: i32, target: i32) -> i32 {
    let mut ops = 0;
    let mut t = target;
    while t > start_value {
      if t % 2 == 0 { t /= 2; } else { t += 1; }
      ops += 1;
    }
    ops + start_value - t
  }
}