PROBLEM DESCRIPTION
Given an array of real numbers greater than zero in form of strings. Find if there exists a triplet (a,b,c) such that 1 < a+b+c < 2. Return 1 for true or 0 for false.
O(n) solution is expected.
Note: You can assume the numbers in strings don’t overflow the primitive data type and there are no leading zeroes in numbers. Extra memory usage is allowed.
SOLUTION
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public class Solution {
public int solve(String[] A) {
// Get the length of the input array
int n = A.length;
// If the array has less than 3 elements, it's not possible to form triplets
if(n < 3) return 0;
// Convert the input string array to a double array for numeric comparison
double[] arr = new double[n];
for(int i=0; i<n; i++){
arr[i] = Double.parseDouble(A[i]);
}
// Sort the array in ascending order
Arrays.sort(arr);
// Initialize two pointers, l and r, representing the leftmost and rightmost elements of the array
int l=0;
int r=n-1;
// Loop until there are at least 3 elements between the pointers
while(r-l+1 >= 3){
// Calculate the middle index
int m = (l+r)/2;
// Calculate the sum of the current triplet
double currentSum = arr[l] + arr[m] + arr[r];
// If the sum is greater than 2.0, move the right pointer to the left
if(currentSum > 2.0){
r--;
}
// If the sum is less than 1.0, move the left pointer to the right
else if(currentSum < 1.0){
l++;
}
// If the sum is between 1.0 and 2.0, return 1 (true)
else{
return 1;
}
}
// If no triplet is found, return 0 (false)
return 0;
}
}