游戏的最优策略|特殊金币

给定一排银币，其中有一个特殊的金币。两名玩家玩游戏，每走一步，玩家必须从行的左端或右端取出一枚硬币，取出特殊硬币的玩家赢得游戏。任务是找到游戏的赢家。

例子：

Input: str = “GSSS” 
Output: First 
The first player directly removes the special gold coin.

Input: str = “SGS” 
Output: Second 
Irrespective of which coin the first player removes, the special 
gold coin becomes exposed and is removed by the second player. 
 

方法：举几个例子可以看出，如果银币的数量是奇数，则第一个玩家获胜，否则第二个玩家获胜。特殊情况下，金币在角落时，无论银币多少，先到者为赢家。

下面是上述方法的实现：

C++

// C++ implementation of the approach
#include 
using namespace std;
 
// Function to return the
// winner of the game
string getWinner(string str, int len)
{
     
    // To store the count of silver coins
    int total = 0;
     
    if(str[0]=='G' ||str[len-1]=='G')
        return "First";
    else{
        for (int i = 0; i < len; i++) {
 
            // Update the position of
           // the gold coin
            if (str[i] == 'S') {
                total++;
            }
        }
 
        // First player will win the game
        if ((total % 2) == 1)
            return "First";
        return "Second";
    }
}
 
// Driver code
int main()
{
    string str = "GSSS";
    int len = str.length();
 
    cout << getWinner(str, len);
 
    return 0;
}

Java

// Java implementation of the approach
import java.util.*;
 
class GFG
{
 
// Function to return the
// winner of the game
static String getWinner(String str, int len)
{
 
    // To store the count of silver coins
    int total = 0;
    for (int i = 0; i < len; i++)
    {
 
        // Update the position of
        // the gold coin
        if (str.charAt(i) == 'S')
        {
            total++;
        }
    }
 
    // First player will win the game
    if ((total % 2) == 1)
        return "First";
    return "Second";
}
 
// Driver code
public static void main(String []args)
{
    String str = "GSSS";
    int len = str.length();
 
    System.out.println(getWinner(str, len));
}
}
 
// This code is contributed by Surendra_Gangwar

Python3

# Python3 implementation of the approach
 
# Function to return the
# winner of the game
def getWinner(string, length) :
 
    # To store the count of silver coins
    total = 0;
    for i in range(length) :
 
        # Update the position of
        # the gold coin
        if (string[i] == 'S') :
            total += 1;
 
    # First player will win the game
    if ((total % 2) == 1) :
        return "First";
    return "Second";
 
# Driver code
if __name__ == "__main__" :
 
    string = "GSSS";
    length = len(string);
 
    print(getWinner(string, length));
     
# This code is contributed by kanugargng

C#

// C# implementation of the approach
using System;
 
class GFG
{
 
// Function to return the
// winner of the game
static String getWinner(String str, int len)
{
 
    // To store the count of silver coins
    int total = 0;
    for (int i = 0; i < len; i++)
    {
 
        // Update the position of
        // the gold coin
        if (str[i] == 'S')
        {
            total++;
        }
    }
 
    // First player will win the game
    if ((total % 2) == 1)
        return "First";
    return "Second";
}
 
// Driver code
public static void Main(string []args)
{
    string str = "GSSS";
    int len = str.Length;
 
    Console.WriteLine(getWinner(str, len));
}
}
 
// This code is contributed by rrrtnx.

Javascript

 
// Javascript implementation of the approach
 
// Function to return the
// winner of the game
function getWinner(str, len)
{
     
    // To store the count of silver coins
    var total = 0;
     
    if (str[0] == 'G' || str[len - 1] == 'G')
        return "First";
    else
    {
        for(var i = 0; i < len; i++)
        {
            // Update the position of
            // the gold coin
            if (str[i] == 'S')
            {
                total++;
            }
        }
 
        // First player will win the game
        if ((total % 2) == 1)
            return "First";
             
        return "Second";
    }
}
 
// Driver code
var str = "GSSS";
var len = str.length;
 
document.write(getWinner(str, len));
 
// This code is contributed by importantly
 

输出：

First

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