Given an array of n integers nums, a 132 pattern is a subsequence of three integers nums[i], nums[j] and nums[k] such that i < j < k and nums[i] < nums[k] < nums[j].
Return true if there is a 132 pattern in nums, otherwise, return false.
Example 1:
Input: nums = [1,2,3,4]
Output: false
Explanation: There is no 132 pattern in the sequence.
Example 2:
Input: nums = [3,1,4,2]
Output: true
Explanation: There is a 132 pattern in the sequence: [1, 4, 2].
Example 3:
Input: nums = [-1,3,2,0]
Output: true
Explanation: There are three 132 patterns in the sequence: [-1, 3, 2], [-1, 3, 0] and [-1, 2, 0].
Constraints:
- n == nums.length
- 1 <= n <= 2 * 105
- -109 <= nums[i] <= 109
class Solution {
public boolean find132pattern (int[] nums) {
Stack <Integer> stack = new Stack ();
int second = Integer.MIN_VALUE;
for (int i = nums.length - 1; i >= 0; i--) {
if (nums [i] < second)
return true;
while (!stack.isEmpty() && nums [i] > stack.peek ())
second = stack.pop ();
stack.push (nums [i]);
}
return false;
}
}