L845 Longest Mountain in Array

Longest Mountain in Array problem

Longest Mountain in Array leetcode

solution

class Solution {
    public int longestMountain(int[] array) {
        int answer = 0;
		for(int i=1;i<array.length-1;){
			boolean isPeak = array[i-1] < array[i] && array[i+1] < array[i];
			if(!isPeak){
				i += 1;
				continue;
			}
			int leftIdx = i - 2;
			while(leftIdx >= 0 && array[leftIdx] < array[leftIdx+1]) {
				leftIdx -= 1;
			}
			int rightIdx = i + 2;
			while(rightIdx < array.length && array[rightIdx] < array[rightIdx -1]){
				rightIdx += 1;
			}
			int currentLength = rightIdx - leftIdx -1;
			if(currentLength > answer){
				answer = currentLength;
			} 
			i = rightIdx;
		}
    return answer;
    }
}

For this problem, we can simply find the peaks in the array. When we find the peak, we can loop to the left and the right and find the length of the peak. O(n) time | O(1) space