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A zero indexed array A consisting of N integers is given. A triplet (P,Q,R) is called a triangle 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]

The perimeter of such a triangle equals A[P] + A[Q] + A[R].

For example A is {10,2,5,1,8,20}

Triplet(0,2,4) is a triangle and its perimeter 10+5+8 = 23. There is no any other triangle with a larger perimeter.

Write a function that given a zero indexed array A of N integers, returns the maximum perimeter of any triangle in this array. The function should return -1 if there are no triangles.

import java.util.Arrays;

/**
 *
 * @author alikatkar
 */
public class TriangleQuestion {

    private boolean isTriangle(int a, int b, int c) {
        return (a + b) > c && (a + c) > b && (b + c) > a;
    }

    public int solution(int[] A) {
        int result = -1;
        int len = A.length;

        //Sort the array
        Arrays.sort(A);
        for (int p = 0; p < len - 2; p++) {
            for (int q = p+1; q < len - 1; q++) {
                for (int r = q+1; r < len; r++) {
                    if (isTriangle(A[p], A[q], A[r])) {
                        int perimeter = A[p] + A[q] + A[r];
                        if (perimeter > result) {
                            result = perimeter;
                        }
                    }

                }
            }
        }
        return result;
    }

    public static void main(String[] args) {

        int[] A = {
            10, 2, 5, 1, 8, 20
        };

        TriangleQuestion q = new TriangleQuestion();
        int x = q.solution(A);
        System.out.println("x:" + x);
    }
}