Find in Mountain Array LeetCode solution in Java

1
class Solution {
2
  public int findInMountainArray(int target, MountainArray mountainArr) {
3
    int peak = findPeak(mountainArr);
4

5
    int left = binary(0, peak, mountainArr, target, true);
6
    if (left != -1) {
7
      return left;
8
    }
9
    int right = binary(peak + 1, mountainArr.length() - 1, mountainArr, target, false);
10
    return right;
11
  }
12

13
  static int findPeak(MountainArray mountainArr) {
14
    int start = 0;
15
    int end = mountainArr.length() - 1;
16

17
    while (start < end) {
18
      int mid = start + ((end - start) / 2);
19

20
      if (mountainArr.get(mid) < mountainArr.get(mid + 1)) {
21
        start = mid + 1;
22
      } else {
23
        end = mid;
24
      }
25
    }
26
    return start;
27
  }
28

29
  static int binary(int low, int high, MountainArray arr, int target, boolean left) {
30
    while (low <= high) {
31
      int mid = low + ((high - low) / 2);
32
      if (target < arr.get(mid)) {
33
        if (left) {
34
          high = mid - 1;
35
        } else {
36
          low = mid + 1;
37
        }
38
      } else if (target > arr.get(mid)) {
39
        if (left) {
40
          low = mid + 1;
41
        } else {
42
          high = mid - 1;
43
        }
44
      } else {
45
        return mid;
46
      }
47
    }
48
    return -1;
49
  }
50
}