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#1884
Medium Algorithms

Egg drop with 2 eggs and n floors

Math Dynamic Programming
74.6% acceptance
Feb 25, 2026
1541
163
You are given two identical eggs and a building with n floors. Find the minimum number of moves to determine the critical floor f with certainty.

Solution

Rust
Time O(n)
Space O(1)
LeetCode
solution.rs
impl Solution {
  pub fn two_egg_drop(n: i32) -> i32 {
    // With t moves, we can cover t*(t+1)/2 floors.
    // Find smallest t where t*(t+1)/2 >= n.
    let mut t = 1;
    while t * (t + 1) / 2 < n {
      t += 1;
    }
    t
  }
}