Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.
Formally the function should:
Return true if there exists i, j, k
such that arr[i] < arr[j] < arr[k] given 0 ≤ i < j < k ≤ n-1 else return false.
Your algorithm should run in O(n) time complexity and O(1) space complexity.
Examples:
Given [1, 2, 3, 4, 5]
,
return true
.
Given [5, 4, 3, 2, 1]
,
return false
.
class Solution {
public boolean increasingTriplet(int[] nums) {
if(nums.length<3) return false;
int first=Integer.MAX_VALUE;
int second=Integer.MAX_VALUE;
int third=Integer.MAX_VALUE;
for(int i=0;i<nums.length;i++){
if(nums[i]>=third) continue;
else if(nums[i]>second&&nums[i]<third){
third=nums[i];
}else if(nums[i]>first&&nums[i]<=second){
second=nums[i];
}else{
first=nums[i];
}
}
return third<Integer.MAX_VALUE;
}
}