Approach #1: Linear Scan [Accepted]
Intuition and Algorithm
Scan through the array to find the unique largest element m
, keeping track of it's index maxIndex
.
Scan through the array again. If we find some x != m
with m < 2*x
, we should return 1
.
Otherwise, we should return maxIndex
.
Complexity Analysis

Time Complexity: where is the length of
nums
. 
Space Complexity: , the space used by our
int
variables.
Analysis written by: @awice.