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Tested Python solution for LeetCode 747 with 30 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 747 # by problem number
lcpy gen -s largest_number_at_least_twice_of_others # by problem name
nums where the largest integer is unique.
Determine whether the largest element in the array is at least twice as much as every other number in the array. If it is, return the index of the largest element, or return -1 otherwise.
Input: nums = [3,6,1,0]
Output: 1
Explanation: 6 is the largest integer.
For every other number in the array x, 6 is at least twice as big as x.
The index of value 6 is 1, so we return 1.
Input: nums = [1,2,3,4]
Output: -1
Explanation: 4 is less than twice the value of 3, so we return -1.
class Solution:
# Time: O(n)
# Space: O(1)
def dominant_index(self, nums: list[int]) -> int:
largest = second = -1
largest_idx = -1
for i, num in enumerate(nums):
if num > largest:
largest_idx = i
second = largest
largest = num
elif num > second:
second = num
if largest >= 2 * second:
return largest_idx
return -1
| Time | Space |
|---|---|
| O(n) | O(1) |