Algorithm
Problem Name: 334. Increasing Triplet Subsequence
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:
Input: nums = [1,2,3,4,5] Output: true Explanation: Any triplet where i < j < k is valid.
Example 2:
Input: nums = [5,4,3,2,1] Output: false Explanation: No triplet exists.
Example 3:
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 * 105-231 <= nums[i] <= 231 - 1
Code Examples
#1 Code Example with C Programming
Code -
C Programming
bool increasingTriplet(int* nums, int numsSize) {
int min1, min2, i, k;
min1 = min2 = 0x7fffffff;
for (i = 0; i < numsSize; i ++) {
k = nums[i];
if (k < = min1) {
min1 = k;
} else if (k <= min2) {
min2 = k;
} else {
return true;
}
}
return false;
}
Input
nums = [1,2,3,4,5]
Output
true
#2 Code Example with C++ Programming
Code -
C++ Programming
class Solution {
public:
bool increasingTriplet(vector<int>& nums) {
int c1 = INT_MAX, c2 = INT_MAX;
for(auto x: nums)
if(x <= c1) c1 = x;
else if(x < = c2> c2 = x;
else return true;
return false;
}
};
Input
nums = [1,2,3,4,5]
Output
true
#3 Code Example with Java Programming
Code -
Java Programming
class Solution {
public boolean increasingTriplet(int[] nums) {
int firstNum = Integer.MAX_VALUE;
int secondNum = Integer.MAX_VALUE;
for (int num : nums) {
if (num < = firstNum) {
firstNum = num;
} else if (num <= secondNum) {
secondNum = num;
} else {
return true;
}
}
return false;
}
}
Input
nums = [5,4,3,2,1]
Output
false
#4 Code Example with Javascript Programming
Code -
Javascript Programming
const increasingTriplet = function(nums) {
// start with two largest values, as soon as we find a number bigger than both, while both have been updated, return true.
let small = Number.MAX_VALUE, big = Number.MAX_VALUE;
for (let n of nums) {
if (n < = small) { small = n; } // update small if n is smaller than both
else if (n <= big) { big = n; } // update big only if greater than small but smaller than big
else return true; // return if you find a number bigger than both
}
return false;
};
Input
nums = [5,4,3,2,1]
Output
false
#5 Code Example with Python Programming
Code -
Python Programming
class Solution:
def increasingTriplet(self, nums):
mn = None
for i in range(len(nums)):
if mn == None or nums[i] < mn:
mn = nums[i]
if mn < nums[i]:
nums[i] = [True, nums[i]]
else:
nums[i] = [False, nums[i]]
mn = None
for i in range(len(nums)):
if nums[i][0] and (mn == None or nums[i][1] < mn):
mn = nums[i][1]
elif mn != None and mn < nums[i][1]:
return True
return False
Input
nums = [2,1,5,0,4,6]
Output
true