```
public int findPeakElement(int[] nums) {
if (nums == null || nums.length == 0) {
return -1;
}
int start = 0;
int end = nums.length - 1;
while (start + 1 < end) {
int mid = start + (end - start) / 2;
if (nums[mid] < nums[mid + 1]) {
start = mid;
} else {
// From question that given an input array where num[i] ≠ num[i+1]
end = mid;
}
}
if (nums[start] > nums[end]) {
return start;
}
return end;
}
```