Task description: Determine whether a triangle can be built from a given set of edges
An array A consisting of N integers is given. A triplet (P, Q, R) is triangular if 0 ≤ P < Q < R < N and:
- A[P] + A[Q] > A[R],
- A[Q] + A[R] > A[P],
- A[R] + A[P] > A[Q].
For example, consider array A such that: A[0] = 10 A[1] = 2 A[2] = 5 A[3] = 1 A[4] = 8 A[5] = 20
Triplet (0, 2, 4) is triangular.
Write a function:
function solution(A);
that, given an array A consisting of N integers, returns 1 if there exists a triangular triplet for this array and returns 0 otherwise.
For example, given array A such that: A[0] = 10 A[1] = 2 A[2] = 5 A[3] = 1 A[4] = 8 A[5] = 20
the function should return 1, as explained above. Given array A such that: A[0] = 10 A[1] = 50 A[2] = 5 A[3] = 1
the function should return 0.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [0..100,000];
- each element of array A is an integer within the range [−2,147,483,648..2,147,483,647].
function solution(A) {
// write your code in JavaScript (Node.js 4.0.0)
if(A.length < 3) {
return 0;
}
A.sort(function(a, b) {
return a-b;
});
for(var i=2; i<A.length; i++) {
if(validate(A[i-2], A[i-1], A[i])) {
return 1;
}
}
return 0;
}
function validate(val0, val1, val2) {
var result = true;
result = result && (val0 + val1 > val2);
result = result && (val0 + val2 > val1);
result = result && (val1 + val2 > val0);
return result;
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