Leetcode•Apr 14, 2026
132 Pattern
Hazrat Ali
Leetcode
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].
Solution
var find132pattern = function(nums) {
let n = nums.length;
let stack = [];
let second = -Infinity;
for (let i = n - 1; i >= 0; i--) {
if (nums[i] < second) {
return true;
}
while (stack.length && stack[stack.length - 1] < nums[i]) {
second = stack.pop();
}
stack.push(nums[i]);
}
return false;
};