Given N eggs and K floors, the task is to find the minimum number of trials needed in the worst case to find the floor below which all floors are safe. A floor is safe if dropping an egg from it does not break the egg. Please refer n eggs and k floors for more insight.
Input: N = 2, K = 10
The first trial is from 4th floor. Two cases arise after this:
- If egg breaks, we have one egg left so we need three more trials.
- If the egg does not break, the next try is from 7th floor. Again two cases arise.
Notice that if 4th floor is chosen as first floor, 7th as the next floor
and 9 as last floor, the number of trials can never exceed 4.
Input: N = 2, K = 100
Prerequisites: Egg Dropping Puzzle
Approach: Consider this problem in a different way:
Let dp[x][n] is the maximum number of floors that can be checked with given n eggs and x moves.
Then the equation is:
- dp[x][n] = dp[x – 1][n – 1] + dp[x – 1][n] + 1
- If the egg breaks, then we can check dp[x – 1][n – 1] floors.
- If the egg doesn’t break, then we can check dp[x – 1][n] + 1 floors.
which means we take 1 move to a floor,
Since we need to cover k floors, dp[x][n] >= k.
dp[x][n] is similar to the number of combinations and it increases exponentially to k
Below is the implementation of the above approach:
Time Complexity: O(NlogK)
Space Complexity: O(N * K)