CODEWITHSUNDEEP
java
Loren
Loren

Reputation: 95

How to check arithmetic sequence

I want to write a program that looks for three numbers in array that gives an arithmetic sequence of length three - three numbers a,b and c form an arithmetic sequence of length 3 if: b-a = c-b.

The problem is that he code doesn't print "yes" even when it should, it never get into the command if. I guess I have a problem when writing the math command for b-a = c-b.

public static void main (String[] args)  {
    int [] a = new int [args.length - 1];W
    for (int i = 0; i<a.length; i++) {
       a[i] = Integer.parseInt(args[i+1]);
     }
    for (int i = 0; i < a.length - 2; i++) {
       for (int j = i+1; j < a.length - 1; j++) {
          int b = a[i];
          for (int k = j + 1; k < a.length; k++) {
             int c = a[k];
             if (b - a[i] == c - b) {
               System.out.println("yes");
                break;
             }
           }
         }
       }
     }
   }

Upvotes: 0

Views: 2149

Answers (2)

Madhesh
Madhesh

Reputation: 69

This works:

public static void main(String[] args) {

        int [] a =new int [new Integer(args.length)];
        for (int i = 0; i<a.length; i++) {
               a[i] = Integer.parseInt(args[i]);
        }

        for(int j=0;j<a.length;j++){

        if(j+2<a.length){           
        if(a[j+1]-a[j] ==a[j+2] - a[j+1])
        System.out.println("Yes........." +a[j] +""+ a[j+1] +"" +a[j+2]);

        }
    }
}

tested with 2 3 4 6(2 3 4 is sequence) and 1 3 5 7 (1 3 5 and 3 5 7 are sequence)

Upvotes: 1

dsharew
dsharew

Reputation: 10665

I think this is what you want:

Changes:

  1. First sort the array
  2. When you break from the inner most loop, you must also break from all the outer loops (check code below) 
Arrays.sort(a);

outerLoop:
for (int i = 0; i < a.length - 2; i++) {

    for(int j = i+1; j < a.length - 1; j++){

        for(int k = j+1; k < a.length; k++){

            if(a[j] - a[i] == a[k] - a[j]){
                System.out.println("yes");
                break outerLoop;
            }

        }

    }

}

Update:
You are missing the first element of the array because of this code: 

int [] a = new int [args.length - 1]
for (int i = 0; i<a.length; i++) {
       a[i] = Integer.parseInt(args[i+1]);
     }

Change it to: 

int [] a = new int [args.length]
for (int i = 0; i<a.length; i++) {
       a[i] = Integer.parseInt(args[i]);
     }

Upvotes: 1

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