Peak Index in a Mountain Array
给一个数组, 找一个index,比左大比右小, 这个题前提是这个index一定存在, 省去很多corn cases的判断, 直接二分找
class Solution {
public int peakIndexInMountainArray(int[] A) {
int start = 0, end = A.length - 1;
while (start < end) {
int mid = start + (end - start) / 2;
if (A[mid] < A[mid + 1])
start = mid + 1;
else
end = mid;
}
return start;
}
}