How to begin with Competitive Programming?

At the very beginning to competitive programming, barely anyone knows the coding style to be followed. Below is an example to help you understand how problems are crafted in competitive programming.

Let us consider below problem statement as an example.
Problem Statement:

Linear Search: Given an integer array and an element x, find if element is present in array or not. If element is present, then print index of its first occurrence. Else print -1.

Input:
First line contains an integer, the number of test cases ‘T’. Each test case should be an integer. Size of the array ‘N’ in the second line. In the third line, input the integer elements of the array in a single line separated by space. Element X should be inputted in the fourth line, i.e., after entering the elements of array. Repeat the above steps second line onwards for multiple test cases.

Output:
Print the output in a separate line returning the index of the element X. If the element is not present, then print -1.

Constraints:
1 <= T <= 100
1 <= N <= 100
1 <= Arr[i] <= 100

Example Input and Output for Your Program:

Input:
2
4
1 2 3 4
3
5
10 90 20 30 40 
40
Output:
2
4

There are 2 test cases (Note 2 at the beginning of input)
Test Case 1: Input: arr[] = {1, 2, 3, 4},  
                    Element to be searched = 3.
             Output:  2
             Explanation: 3 is present at index 2.

Test Case 2: Input: arr[] = {10, 90, 20, 30, 40}, 
                    Element to be searched = 40.
             Output:  4
             Explanation: 40 is present at index 4.

       

            // A Sample C++ program for beginners with Competitive Programming 
#include 
using namespace std; 

// This function returns index of element x in arr[] 
int search(int arr[], int n, int x) 
{ 
	for (int i = 0; i < n; i++) 
	{ 
		// Return the index of the element if the element 
		// is found 
		if (arr[i] == x) 
			return i; 
	} 

	// return -1 if the element is not found 
	return -1; 
} 

int main() 
{ 
	// Note that size of arr[] is considered 100 according to 
	// the constraints mentioned in problem statement. 
	int arr[100], x, t, n; 

	// Input the number of test cases you want to run 
	cin >> t; 

	// One by one run for all input test cases 
	while (t--) 
	{ 
		// Input the size of the array 
		cin >> n; 

		// Input the array 
		for (int i=0; i> arr[i]; 

		// Input the element to be searched 
		cin >> x; 

		// Compute and print result 
		cout << search(arr, n, x) << endl; 
	} 
	return 0; 
}