# Find the winner of a game of donating i candies in every i-th move

Given two integers **X **and **Y** representing the number of candies allocated to players **A** and **B** respectively, where both the players indulge in a game of donating **i** candies to the opponent in every **i**^{th} move. Starting with player **A**, the game continues with alternate turns until a player is unable to donate the required amount of candies and loses the game, the task is to find the winner of the game.

**Examples:**

Input:X = 2, Y = 3Output:AExplanation:The game turns out in the following manner:

Step

X

Y

0

2

3

1

1

4

2

3

2

3

0

5

4

4

1

Since A fails to donate 5 candies in the 5

^{th}step, B wins the game.

Input:X = 2, Y = 1Output:BExplanation:The game turns out in the following manner:

Step X Y 0 2 1 1 1 2 2 3 0 3 0 3 Since B fails to give 4 candies in the 4

^{th}step, A wins the game.

**Approach: **The idea is to solve the problem based on the following observation:

Step

Number of candies

Possessed by ANumber of candies

Possessed by B0

X

Y

1

X – 1

Y + 1

2

X – 1 + 2 = X + 1

Y + 1 – 2 = Y – 1

3

X – 2

Y + 2

4

X + 2

Y – 2

- The player whose candies reduce to 0 first, will not be having enough candies to give in the next move.
- Count of candies of player A decreases by 1 in odd moves.
- Count of candies of player B decreases by 1 in even moves.

Follow the steps below to solve the problem**:**

- Initialize two variables, say
**chanceA**and**chanceB,**representing the number of moves in which the number of candies possessed by a player reduces to 0. - Since count of candies of player
**A**decreases by 1 in odd moves,**chanceA = 2 * (X – 1) + 1** - Since count of candies of player
**B**decreases by 1 in even moves,**chanceB = 2 * Y** - If
**chanceA < chanceB**, then**B**will be the winning player. - Otherwise,
**A**will be the winning player. - Print the winning player.

Below is the implementation of the above approach:

## C++

`// C++ Program for the` `// above approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to find the winning` `// player in a game of donating i` `// candies to opponent in i-th move` `int` `stepscount(` `int` `a, ` `int` `b)` `{` ` ` `// Steps in which number of` ` ` `// candies of player A finishes` ` ` `int` `chanceA = 2 * a - 1;` ` ` `// Steps in which number of` ` ` `// candies of player B finishes` ` ` `int` `chanceB = 2 * b;` ` ` `// If A's candies finishes first` ` ` `if` `(chanceA < chanceB) {` ` ` `cout << ` `"B"` `;` ` ` `}` ` ` `// Otherwise` ` ` `else` `if` `(chanceB < chanceA) {` ` ` `cout << ` `"A"` `;` ` ` `}` ` ` `return` `0;` `}` `// Driver Code` `int` `main()` `{` ` ` `// Input` ` ` `// Candies possessed` ` ` `// by player A` ` ` `int` `A = 2;` ` ` `// Candies possessed` ` ` `// by player B` ` ` `int` `B = 3;` ` ` `stepscount(A, B);` ` ` `return` `0;` `}` |

## Java

`// Java Program for above approach` `class` `GFG{` ` ` `// Function to find the winning` `// player in a game of donating i` `// candies to opponent in i-th move` `static` `void` `stepscount(` `int` `a, ` `int` `b)` `{` ` ` ` ` `// Steps in which number of` ` ` `// candies of player A finishes` ` ` `int` `chanceA = ` `2` `* a - ` `1` `;` ` ` `// Steps in which number of` ` ` `// candies of player B finishes` ` ` `int` `chanceB = ` `2` `* b;` ` ` `// If A's candies finishes first` ` ` `if` `(chanceA < chanceB)` ` ` `{` ` ` `System.out.print(` `"B"` `);` ` ` `}` ` ` `// Otherwise` ` ` `else` `if` `(chanceB < chanceA)` ` ` `{` ` ` `System.out.print(` `"A"` `);` ` ` `}` `}` `// Driver code` `public` `static` `void` `main(String[] args)` `{` ` ` ` ` `// Input` ` ` `// Candies possessed by player A` ` ` `int` `A = ` `2` `;` ` ` `// Candies possessed by player B` ` ` `int` `B = ` `3` `;` ` ` `stepscount(A, B);` `}` `}` `// This code is contributed by abhinavjain194` |

## Python3

`# Python3 program for the above approach` `# Function to find the winning` `# player in a game of donating i` `# candies to opponent in i-th move` `def` `stepscount(a, b):` ` ` ` ` `# Steps in which number of` ` ` `# candies of player A finishes` ` ` `chance_A ` `=` `2` `*` `a ` `-` `1` ` ` ` ` `# Steps in which number of` ` ` `# candies of player B finishes` ` ` `chance_B ` `=` `2` `*` `b` ` ` ` ` `# If A's candies finishes first` ` ` `if` `(chance_A < chance_B):` ` ` `return` `'B'` ` ` ` ` `# Otherwise ` ` ` `else` `:` ` ` `return` `"A"` `# Driver code` `# Candies possessed by player A ` `A ` `=` `2` `# Candies possessed by player B` `B ` `=` `3` `print` `(stepscount(A, B))` `# This code is contributed by abhinavjain194` |

## C#

`// C# program for the above approach` `using` `System;` `class` `GFG{` ` ` `// Function to find the winning` `// player in a game of donating i` `// candies to opponent in i-th move` `static` `void` `stepscount(` `int` `a, ` `int` `b)` `{` ` ` ` ` `// Steps in which number of` ` ` `// candies of player A finishes` ` ` `int` `chanceA = 2 * a - 1;` ` ` `// Steps in which number of` ` ` `// candies of player B finishes` ` ` `int` `chanceB = 2 * b;` ` ` `// If A's candies finishes first` ` ` `if` `(chanceA < chanceB)` ` ` `{` ` ` `Console.Write(` `"B"` `);` ` ` `}` ` ` `// Otherwise` ` ` `else` `if` `(chanceB < chanceA)` ` ` `{` ` ` `Console.Write(` `"A"` `);` ` ` `}` `}` `// Driver code` `static` `void` `Main()` `{` ` ` ` ` `// Input` ` ` `// Candies possessed by player A` ` ` `int` `A = 2;` ` ` `// Candies possessed by player B` ` ` `int` `B = 3;` ` ` `stepscount(A, B);` `}` `}` `// This code is contributed by abhinavjain194` |

## Javascript

`<script>` `// Javascript program for the above approach` `// Function to find the winning` `// player in a game of donating i` `// candies to opponent in i-th move` `function` `stepscount( a, b)` `{` ` ` `// Steps in which number of` ` ` `// candies of player A finishes` ` ` `let chanceA = 2 * a - 1;` ` ` `// Steps in which number of` ` ` `// candies of player B finishes` ` ` `;let chanceB = 2 * b;` ` ` `// If A's candies finishes first` ` ` `if` `(chanceA < chanceB) {` ` ` `document.write(` `"B"` `);` ` ` `}` ` ` `// Otherwise` ` ` `else` `if` `(chanceB < chanceA) {` ` ` `document.write(` `"A"` `);` ` ` `}` ` ` `return` `0;` `}` `// Driver Code` `// Input` `// Candies possessed` `// by player A` `let A = 2;` `// Candies possessed` `// by player B` `let B = 3;` `stepscount(A, B);` `</script>` |

**Output:**

B

**Time Complexity:** O(1)**Auxiliary Space:** O(1)