Given that you have four slots, and each slot will contain a color red (R), yellow (Y), green (G), blue (B) respectively. For example, if you select YGGR (Slot-1 is yellow, Slots-2 and -3 are green, Slot -4 is red). The colors of slots are not known to you beforehand. You will make a guess about the colors. You might, for example, guess YRGB.

When you guess the correct color for the correct slot, you get a “hit” If you guess a color that exists but is in the wrong slot, you get a “pseudo-hit:’ Note that a slot that is a hit can never count as a pseudo-hit.

Given a guess and a solution, your task is to write a program to calculate the number of hits and pseudo-hits.

Examples:

Input: solution -> RGBY, Guess -> GGRR Output: hit -> 1, pseudohit -> 1 Input: solution -> RGYB, Guess -> YGRR Output: hit -> 1, pseudohit -> 2 Input: solution -> RGYB, Guess -> GGYR Output: hit -> 2, pseudohit -> 1

A **simple solution** will be to traverse both strings simultaneously and check the characters of both strings. If both strings have same character then it is a hit and thus increment the count of hits. If the characters of strings do not match at a position, then traverse the solution string again to see if the character in guess is occurred anywhere in solution string or not, if yes increment count of pseudo hits.**Time Complexity**: O(N*N) , where N is the length of string.

An **efficient solution** is to create a frequency array which stores how many times each character occurs in solution, excluding times when the slot is a “hit”. Then, we iterate through guess to count the number of pseudo-hits.

Below is the implementation of above approach:

## C++

`// CPP code to solve RGYB game` `#include<iostream>` `#include<string>` `using` `namespace` `std;` `int` `hits = 0;` `int` `pseudoHits = 0;` ` ` `// maximum no of colors are 4 RGYB` `int` `MAX_COLORS = 4;` ` ` `// Function to assign code to a slot` `// based on the color they have` `int` `codeOfColor(` `char` `c)` `{` ` ` `switch` `(c) ` ` ` `{` ` ` `case` `'B'` `: ` `return` `0;` ` ` `case` `'G'` `: ` `return` `1;` ` ` `case` `'R'` `: ` `return` `2;` ` ` `case` `'Y'` `: ` `return` `3;` ` ` `default` `:` ` ` `return` `-1;` ` ` `}` `}` ` ` `// Function to calculate number of hits` `// and pseudo hits` `void` `calcResult(string guess, string solution)` `{` ` ` `hits = 0;` ` ` `pseudoHits = 0;` ` ` ` ` `if` `(guess.length() != solution.length())` ` ` `cout<<` `"Incorrect Input"` `<<endl;` ` ` ` ` `// frequency array to store how many times ` ` ` `// each character occurs in solution string ` ` ` `int` `frequencies[MAX_COLORS] ={ 0 };` ` ` ` ` `// Compute hits and build frequency table ` ` ` `for` `(` `int` `i = 0; i < guess.length() ;i++)` ` ` `{` ` ` `if` `(guess[i] == solution[i])` ` ` `hits++;` ` ` ` ` `else` ` ` `{` ` ` `// Only increment the frequency table (which ` ` ` `// will be used for pseudo-hits) if it's not ` ` ` `// a hit. If it's a hit, the slot has already ` ` ` `// been "used." ` ` ` `int` `codecolor = codeOfColor(solution[i]);` ` ` `frequencies[codecolor]++;` ` ` `}` ` ` `}` ` ` ` ` `// Compute pseudo-hits ` ` ` `for` `(` `int` `i = 0; i < guess.length(); i++) ` ` ` `{` ` ` `int` `codecolor = codeOfColor(guess[i]);` ` ` ` ` `if` `(codecolor >= 0 && frequencies[codecolor] > 0` ` ` `&& guess[i] != solution[i]) ` ` ` `{` ` ` `pseudoHits++;` ` ` `frequencies[codecolor]--;` ` ` `}` ` ` `}` ` ` ` ` `cout << ` `"hits -> "` `<< hits << ` `" Pseudo hits -> "` ` ` `<< pseudoHits << endl;` `}` ` ` `// Driver code to test above function` `int` `main()` `{` ` ` `string solution = ` `"GGRR"` `;` ` ` `string guess = ` `"RGBY"` `;` ` ` ` ` `calcResult(solution, guess);` ` ` ` ` `solution = ` `"YGRR"` `;` ` ` `guess = ` `"RGYB"` `;` ` ` ` ` `calcResult(solution, guess);` `}` `// This code is contributed by Sumit Ghosh` |

## Java

`// Java code to solve RGYB game` ` ` `import` `java.util.*;` `import` `java.lang.*;` `import` `java.io.*;` ` ` `class` `CalcRes ` `{` ` ` `static` `int` `hits = ` `0` `;` ` ` `static` `int` `pseudoHits = ` `0` `;` ` ` ` ` `// Function to assign code to a slot` ` ` `// based on the color they have` ` ` `static` `int` `codeOfColor(` `char` `c)` ` ` `{` ` ` `switch` `(c) ` ` ` `{` ` ` `case` `'B'` `: ` `return` `0` `;` ` ` `case` `'G'` `: ` `return` `1` `;` ` ` `case` `'R'` `: ` `return` `2` `;` ` ` `case` `'Y'` `: ` `return` `3` `;` ` ` `default` `:` ` ` `return` `-` `1` `;` ` ` `}` ` ` `}` ` ` ` ` `// maximum no of colors are 4 RGYB` ` ` `static` `int` `MAX_COLORS = ` `4` `;` ` ` ` ` `// Function to calculate number of hits` ` ` `// and pseudo hits` ` ` `static` `void` `calcResult(String guess, String solution)` ` ` `{ ` ` ` `hits = ` `0` `;` ` ` `pseudoHits = ` `0` `;` ` ` ` ` `if` `(guess.length() != solution.length())` ` ` `System.out.println(` `"Incorrect Input"` `);` ` ` ` ` `// frequency array to store how many times ` ` ` `// each character occurs in solution string` ` ` `int` `[] frequencies = ` `new` `int` `[MAX_COLORS];` ` ` ` ` `// Compute hits and build frequency table ` ` ` `for` `(` `int` `i = ` `0` `; i < guess.length(); i++) ` ` ` `{` ` ` `if` `(guess.charAt(i) == solution.charAt(i)) ` ` ` `{` ` ` `hits++;` ` ` `} ` ` ` `else` ` ` `{` ` ` `/* ` ` ` `Only increment the frequency table (which will be ` ` ` `used for pseudo-hits) if it's not a hit. If it's a ` ` ` `hit, the slot has already been "used." ` ` ` `*/` ` ` `int` `codeofcolor = codeOfColor(solution.charAt(i));` ` ` `frequencies[codeofcolor]++;` ` ` `}` ` ` `}` ` ` ` ` `// Compute pseudo-hits ` ` ` `for` `(` `int` `i = ` `0` `; i < guess.length(); i++) ` ` ` `{` ` ` `int` `codeofcolor = codeOfColor(guess.charAt(i));` ` ` `if` `(codeofcolor >= ` `0` `&& frequencies[codeofcolor] > ` `0` `&& ` ` ` `guess.charAt(i) != solution.charAt(i)) ` ` ` `{` ` ` `pseudoHits++;` ` ` `frequencies[codeofcolor]--;` ` ` `}` ` ` `}` ` ` ` ` `System.out.println(` `"hits -> "` `+ hits + ` ` ` `" Pseudo hits -> "` `+ pseudoHits);` ` ` `}` ` ` ` ` ` ` `// Driver Code` ` ` `public` `static` `void` `main(String[] args)` ` ` `{ ` ` ` `String solution = ` `"GGRR"` `;` ` ` `String guess = ` `"RGBY"` `;` ` ` ` ` `calcResult(solution, guess);` ` ` ` ` `solution = ` `"YGRR"` `;` ` ` `guess = ` `"RGYB"` `;` ` ` ` ` `calcResult(solution, guess);` ` ` `}` `}` |

## Python

`# Python code to solve RGYB game` ` ` `hits ` `=` `0` `pseudoHits ` `=` `0` ` ` `# maximum no of colors are 4 RGYB` `MAX_COLORS ` `=` `4` ` ` `# Function to assign code to a slot` `# based on the color they have` `def` `codeOfColor(c):` ` ` `if` `c ` `=` `=` `'B'` `:` ` ` `return` `0` `;` ` ` `elif` `c ` `=` `=` `'G'` `:` ` ` `return` `1` `;` ` ` `elif` `c ` `=` `=` `'R'` `:` ` ` `return` `2` `;` ` ` `elif` `c ` `=` `=` `'Y'` `:` ` ` `return` `3` `;` ` ` `else` `:` ` ` `return` `-` `1` `;` ` ` `# Function to calculate number of hits` `# and pseudo hits` `def` `calcResult(guess, solution):` ` ` `hits ` `=` `0` ` ` `pseudoHits ` `=` `0` ` ` `if` `(` `len` `(guess) !` `=` `len` `(solution)):` ` ` `print` `"Incorrect Input"` ` ` ` ` `# frequency array to store how many times ` ` ` `# each character occurs in solution string ` ` ` `frequencies ` `=` `[` `0` `for` `i ` `in` `range` `(MAX_COLORS)]` ` ` ` ` `# Compute hits and build frequency table ` ` ` `for` `i ` `in` `range` `(` `len` `(guess)):` ` ` `if` `(guess[i] ` `=` `=` `solution[i]):` ` ` `hits ` `+` `=` `1` ` ` `else` `:` ` ` ` ` `# Only increment the frequency table (which ` ` ` `# will be used for pseudo-hits) if it's not ` ` ` `# a hit. If it's a hit, the slot has already ` ` ` `# been "used." ` ` ` `codecolor ` `=` `codeOfColor(solution[i])` ` ` `frequencies[codecolor] ` `+` `=` `1` ` ` ` ` `# Compute pseudo-hits ` ` ` `for` `i ` `in` `range` `(` `len` `(guess)):` ` ` `codecolor ` `=` `codeOfColor(guess[i])` ` ` `if` `codecolor >` `=` `0` `and` `frequencies[codecolor] > ` `0` `and` `guess[i] !` `=` `solution[i]:` ` ` `pseudoHits ` `+` `=` `1` ` ` `frequencies[codecolor] ` `-` `=` `1` ` ` `print` `"hits -> "` `, hits, ` `" Pseudo hits -> "` `, pseudoHits` ` ` `# Driver code to test above function` `solution ` `=` `"GGRR"` `guess ` `=` `"RGBY"` `calcResult(solution, guess)` ` ` `solution ` `=` `"YGRR"` `guess ` `=` `"RGYB"` `calcResult(solution, guess)` ` ` `#This code is contributed by Sachin Bisht` |

## C#

`// C# code to solve RGYB game` `using` `System;` ` ` `class` `GFG {` ` ` ` ` `static` `int` `hits = 0;` ` ` `static` `int` `pseudoHits = 0;` ` ` ` ` `// Function to assign code to a slot` ` ` `// based on the color they have` ` ` `static` `int` `codeOfColor(` `char` `c)` ` ` `{` ` ` `switch` `(c) ` ` ` `{` ` ` `case` `'B'` `: ` `return` `0;` ` ` `case` `'G'` `: ` `return` `1;` ` ` `case` `'R'` `: ` `return` `2;` ` ` `case` `'Y'` `: ` `return` `3;` ` ` `default` `: ` `return` `-1;` ` ` `}` ` ` `}` ` ` ` ` `// maximum no of colors are 4 RGYB` ` ` `static` `int` `MAX_COLORS = 4;` ` ` ` ` `// Function to calculate number of hits` ` ` `// and pseudo hits` ` ` `static` `void` `calcResult(` `string` `guess, ` `string` `solution)` ` ` `{ ` ` ` `hits = 0;` ` ` `pseudoHits = 0;` ` ` ` ` `if` `(guess.Length != solution.Length)` ` ` `Console.Write(` `"Incorrect Input"` `);` ` ` ` ` `// frequency array to store how many` ` ` `// times each character occurs in` ` ` `// solution string` ` ` `int` `[]frequencies = ` `new` `int` `[MAX_COLORS];` ` ` ` ` `// Compute hits and build frequency table ` ` ` `for` `(` `int` `i = 0; i < guess.Length; i++) ` ` ` `{` ` ` `if` `(guess[i] == solution[i]) ` ` ` `{` ` ` `hits++;` ` ` `} ` ` ` `else` ` ` `{` ` ` ` ` `/* Only increment the frequency table` ` ` `(which will be used for pseudo-hits)` ` ` `if it's not a hit. If it's a hit, the` ` ` `slot has already been "used." */` ` ` `int` `codeofcolor = codeOfColor(solution[i]);` ` ` `frequencies[codeofcolor]++;` ` ` `}` ` ` `}` ` ` ` ` `// Compute pseudo-hits ` ` ` `for` `(` `int` `i = 0; i < guess.Length; i++) ` ` ` `{` ` ` `int` `codeofcolor = codeOfColor(guess[i]);` ` ` `if` `(codeofcolor >= 0 && ` ` ` `frequencies[codeofcolor] > 0 && ` ` ` `guess[i] != solution[i]) ` ` ` `{` ` ` `pseudoHits++;` ` ` `frequencies[codeofcolor]--;` ` ` `}` ` ` `}` ` ` ` ` `Console.WriteLine(` `"hits -> "` `+ hits + ` ` ` `" Pseudo hits -> "` `+ pseudoHits);` ` ` `}` ` ` ` ` `// Driver Code` ` ` `public` `static` `void` `Main()` ` ` `{ ` ` ` `string` `solution = ` `"GGRR"` `;` ` ` `string` `guess = ` `"RGBY"` `;` ` ` ` ` `calcResult(solution, guess);` ` ` ` ` `solution = ` `"YGRR"` `;` ` ` `guess = ` `"RGYB"` `;` ` ` ` ` `calcResult(solution, guess);` ` ` `}` `}` ` ` `// This code is contributed by nitin mittal.` |

Output:

hits -> 1 Pseudo hits -> 1 hits -> 1 Pseudo hits -> 2

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

This article is contributed by **Mr. Somesh Awasthi**. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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