Increasing Triplet Subsequence Problem
Description
LeetCode Problem 334.
Given an integer array nums, return true if there exists a triple of indices (i, j, k) such that i < j < k and nums[i] < nums[j] < nums[k]. If no such indices exists, return false.
Example 1:
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Input: nums = [1,2,3,4,5]
Output: true
Explanation: Any triplet where i < j < k is valid.
Example 2:
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Input: nums = [5,4,3,2,1]
Output: false
Explanation: No triplet exists.
Example 3:
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Input: nums = [2,1,5,0,4,6]
Output: true
Explanation: The triplet (3, 4, 5) is valid because nums[3] == 0 < nums[4] == 4 < nums[5] == 6.
Constraints:
- 1 <= nums.length <= 5 * 10^5
- -2^31 <= nums[i] <= 2^31 - 1
Sample C++ Code
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class Solution {
public:
bool increasingTriplet(vector<int>& nums) {
int len = nums.size();
if (len < 3)
return false;
int a = INT_MAX, b = INT_MAX;
for (int i = 0; i < len; i ++) {
if (nums[i] <= a)
a = nums[i];
else if (nums[i] <= b)
b = nums[i];
else
return true;
}
return false;
}
};