1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
| class Solution {
public:
int findInMountainArray(int target, MountainArray &mountainArr) {
const int n = mountainArr.length();
int topIndex = findTopIndex(mountainArr, 0, n - 1);
if (mountainArr.get(topIndex) == target) return topIndex;
int idx = findFromSortedArr(mountainArr, 0, topIndex - 1, target);
if (idx >= 0) return idx;
return findFromReversedArr(mountainArr, topIndex + 1, n - 1, target);
}
private:
int findTopIndex(MountainArray& mountainArr, int left, int right) {
while (left < right) {
int mid = (right - left) / 2 + left;
if (mountainArr.get(mid) < mountainArr.get(mid + 1))
left = mid + 1;
else
right = mid;
}
return left;
}
int findFromSortedArr(MountainArray& mountainArr, int left, int right, int target) {
while (left < right) {
int mid = (right - left) / 2 + left;
if (mountainArr.get(mid) < target)
left = mid + 1;
else
right = mid;
}
return mountainArr.get(left) == target ? left : -1;
}
int findFromReversedArr(MountainArray& mountainArr, int left, int right, int target) {
while (left < right) {
int mid = (right - left + 1) / 2 + left;
if (mountainArr.get(mid) < target)
right = mid - 1;
else
left = mid;
}
return mountainArr.get(left) == target ? left : -1;
}
};
|