Gain insights into competitive programming, explore C++ skills with theory, code samples, practice problems, and master faster implementation for contests like ACM ICPC, Google CodeJam, and HackerCup.

Competitive programming can be a great way to build out your programming skills, get on any major company’s radar, and earn a little extra cash along the way.

In this course, you will learn to prepare for competitive programming contests like ACM ICPC, Google CodeJam, Facebook HackerCup, and many more.

Each topic is broken down with a healthy mix of theory, code samples, step-by-step solved sample problems, illustrations, useful practice problems, and tips and tricks for faster implementation.

You will need some solid C++ foundations coming into this course, but by the end it, you will be confident enough in your C++ skills to take home the win.

Competitive Programming in C++: The Keys to Success

# Problem statement

Given two very long integers $A$ and $B$. You have to determine which is bigger or if they are equal. *Leading zeroes are allowed.*


**Input format**

The first line contains a non-negative integer, $A$.

The second line contains a non-negative integer, $B$.

$A$,$B$ may contain leading zeroes. Each of them consists of no more than $10^6$ digits.

**Output format**

Print a single character:

* `A` - if $A > B$
* `B` - if $B > A$
* `=` - If numbers are equal

---

# Sample
**Input 1**
```
6 
19
```
**Output 1**
```
B
```
**Input 2**
```
23567
0023534
```
**Output 2**
```
A
```
**Input 3**
```
63
0063
```
**Output 3**
```
=
```

---

# Explanation
**Sample 2**: The numbers without leading zeros are `23` and `12`. We'll print `A` since $23 > 12$.

---

# Solution
First of all, the number of digits can be $10^6$. So clearly, no integer data type is enough *(`int` is 10 digits)*. We **have** to process the input as a string. 

Before comparing the string, we remove the trailing zeros from both the numbers.

Comparing two numbers as a string without leading zeros has three cases:

1. $len(A) > len(B)$ - A is larger
2. $len(A) < len(B)$ - B is larger
3. $len(A) = len(B)$ - First digit from the left that is different. If all digits are same, print `=`.

---

# Removing leading zeros
Removing the first character one by one in order to remove the leading zeroes will be an $O(N^2)$ operation. A better way to do this would be to create a new string without leading zeros.


This would remove leading zeros in $O(N)$.

In this lesson, we'll discuss another string manipulation problem.

Introduction

Complexity Analysis

Number Theory

Arrays and Vectors

Sieve of Eratosthenes

Strings

Sorting

Linked List

Stack

Queue

Binary Tree

2 Pointers

Heap

Binary Search Tree

Balanced Binary Search Tree

Course Conclusion

Solved Problem - Compare Numbers

Problem statement