# 456. 132 Pattern | LeetCode Solution

## 456. 132 Pattern | LeetCode 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`.

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:
bool find132pattern(vector<int> &nums)
{
int s3 = INT_MIN;

stack<int> st;

for (int i = nums.size() - 1; i >= 0; i--)
{
if (nums[i] < s3)
return true;
while (!st.empty() && nums[i] > st.top())
{
s3 = st.top();
st.pop();
}
st.push(nums[i]);
}
return false;
}
};