Data Structure and algorithm

Algorithms: Way of Solving well-specified computational problem.
                                                 OR
         Sequence of operation for solving a specific problem.


Euclid's Algorithm:
Used to find Greatest Common Divisor(GCD) of two positive integers.

Consider two positive integers m and n , m>n.
Step 1: Divide m by n, and let the remainder be r
Step 2: if r = 0 the algorithm ends, n is the GCD.
Step 3: If r is not 0 then, Set m = n; and n = r, go back to step1 and continue till, r = 0.

Note: This is a recursive algorithms as it calls over and over.

/**
     * This method takes two positive integers and finds their                                       * GreatestCommonFactor(GCD) using
     * Euclid's algorithm
     * @param a
     * @param b
     * @return
     */
public int greatestCommonFactor(int a, int b){
        if(b == 0) return a;
        return greatestCommonFactor(b, a%b);
}

Recursion Algorithm:

Merge Sort: A recursive algorithm for sorting large set of data.We merge two unsorted arrays.
This is a merge sort diagram and flow structure.

For more details :
https://www.hackerearth.com/practice/algorithms/sorting/merge-sort/tutorial/