leetcode 456 - 132 Pattern

https://leetcode.com/problems/132-pattern/
https://leetcode.com/problems/132-pattern/solution/

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.

Follow up: The O(n^2) is trivial, could you come up with the O(n logn) or the O(n) solution?

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 <= 10^4
-109 <= nums[i] <= 10^9

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class Solution {
public:
bool find132pattern(vector<int>& nums) {
int size = nums.size();

vector<int> mins(size);

for (int i = 0; i < size; i++) {
if (i == 0)
mins[i] = nums[i];
else
mins[i] = min(mins[i-1], nums[i]);
}

stack<int> stk;

for (int i = size - 1; i >= 0; i--) {
if (nums[i] > mins[i]) {
while (!stk.empty() && mins[i] >= stk.top())
stk.pop();

if (!stk.empty() && nums[i] > stk.top())
return true;

stk.push(nums[i]);
}
}

return false;
}
};