Poison

1095. Find in Mountain Array

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class Solution {
    public int findInMountainArray(int target, MountainArray mountainArr) {
        int peakIndex = findPeakIndex(mountainArr);
        int index = binarySearch(mountainArr, 0, peakIndex, true, target);
        if (index != -1) {
            return index;
        } else {
            return binarySearch(mountainArr, peakIndex, mountainArr.length() - 1, false, target);
        }
    }

    private int binarySearch(MountainArray mountainArr, int left, int right, boolean asc, int target) {
        while (left <= right) {
            int mid = (left + right) >>> 1;
            int midVal = mountainArr.get(mid);
            if (midVal < target) {
                if (asc) {
                    left = mid + 1;
                } else {
                    right = mid - 1;
                }
            } else if (midVal > target) {
                if (asc) {
                    right = mid - 1;
                } else {
                    left = mid + 1;
                }
            } else {
                return mid;
            }
        }

        return -1;
    }

    private int findPeakIndex(MountainArray mountainArr) {
        int left = 0, right = mountainArr.length() - 1;
        while (left < right) {
            int mid = (left + right) >>> 1;
            int midVal = mountainArr.get(mid), nextVal = mountainArr.get(mid + 1);
            if (midVal < nextVal) {
                left = mid + 1;
            } else {
                right = mid;
            }
        }

        return left;
    }
}
Reference

1095. Find in Mountain Array