#include <iostream>
#include <string>
using std::cout;
using std::string;
using std::cin;
using std::endl;
   
void K_O(string* , string);   //這個函式

void pfdcp(string et, string pf[5][5] , int alp[3][26] , string nct[]);  //解密函式

//ct即cleartext，pf即密碼矩陣，alp即放了pf座標的字母表 
void pfecp(string ct, string pf[5][5] , int alp[3][26] , string eText[]);  //加密函式
 

int main()
{
    string key; //金鑰 
    string cleartext;  //明文  
    cout << "請輸入金鑰： " ;getline(cin, key);
    cout << "請輸入明文: " ;getline(cin, cleartext);
    string ecptext = cleartext;
    cout << "預設的密文： " << ecptext << endl; 
//    cout << key<<key.length() << endl;
    string playfair[5][5] ;  //密碼矩陣
    string another;   //約定填充的字母
    cout << "輸入約定的填充字母： ";cin >> another; 
	
	 
	
	string eText[cleartext.length()];    //
	string cText[ecptext.length()];
	 
    //去重
	int alp[3][26] = {{0*26},{0*26},{0*26}};
	int abLength=0;
    for(int i=0 ; i<key.length() ; i++){
    	
    	 if(alp[0][((int)key[i]) - 97] == 0){ //應該用一個臨時變數放這個強轉 
    	 	if(key[i] == 'i'||key[i] == 'j'){  //讓i、j變得相同 
    			alp[0][8]=alp[0][9]=1;
    			playfair[abLength/5][abLength%5] = key[i];
    			//新增alp在playfair裡面的對應座標
    			alp[1][8]=alp[1][9] = abLength/5;
    			alp[2][8]=alp[2][9] = abLength%5;
			 	abLength++;
			}
			else{
				alp[0][((int)key[i]) - 97] = 1;
    			playfair[abLength/5][abLength%5] = key[i];
    			alp[1][((int)key[i]) - 97] = abLength/5;
				alp[2][((int)key[i]) - 97] = abLength%5;
    			abLength++;
			}
		}
			
	}
	
	//檢查 
//	for(int i=0; i<5 ; i++){
//		for(int j=0 ; j<5 ; j++)
//		cout << playfair[i][j] ;
//		cout << endl;
//	}

//填充Playfair矩陣 
	for(int i = 0 ; i<26 ; i++){
			if (i == 8){
				if(alp[0][i] == 0){
					char x =i+97;
					playfair[abLength/5][abLength%5] = x;
					alp[1][i] = abLength/5;
					alp[2][i] = abLength%5; 
					alp[1][i+1] = abLength/5;
					alp[2][i+1] = abLength%5;
    				abLength++;
    				alp[0][i+1] = 1;
				}
			}
			else if(alp[0][i] == 0 ){
				char x =i+97;
				playfair[abLength/5][abLength%5] = x;
				alp[1][i] = abLength/5;
				alp[2][i] = abLength%5; 
    			abLength++;
			} 
		
	} 
		//填充檢查 
	for(int i=0; i<5 ; i++){
		for(int j=0 ; j<5 ; j++)
		cout << playfair[i][j] << " | ";
		cout << endl;
 	}
 	//檢查alp中的陣列下標 
// 	for(int i=0 ; i<3 ; i++){
// 		for(int j=0 ; j<26 ; j++)
// 			cout << alp[i][j] <<" | " ;
// 		cout << endl;
//	 }
 	
 	//明文預處理 
	K_O(&cleartext, another);
	//明文輸出檢查 
	cout <<"明文預處理輸出檢查： " << cleartext <<endl;
	
	pfecp(cleartext , playfair , alp , eText);
	
	cout << "密文: ";
	for(int i=0; i<cleartext.length() ; i++)
	cout << eText[i] ;
	cout << endl;
	
	pfdcp(ecptext , playfair , alp , cText);
	cout << "明文： ";
	for(int i=0 ; i<ecptext.length() ; i++)
	cout << cText[i] ;
 
	return 0;
}

int check(string text){
	int i=0;
	for(; i<text.length()-2 ; i+=2){
		if(text[i] == text[i+1] ||(text[i] == 'i' && text[i+1] == 'j')||(text[i] == 'j' && text[i+1] == 'i'))
			return i;
	}
	if (i+1<text.length()){
		if(text[i] == text[i+1] ||(text[i] == 'i' && text[i+1] == 'j')||(text[i] == 'j' && text[i+1] == 'i'))
			return i;
		else return -1;
	}
	else return text.length()-1;
} 

//明文的處理 
//隱患：當字尾是z，或者中間插入之前是z，那就麻煩了 
void K_O(string *str , string z){
	int indi = check(*str);
	if (indi == str->length()-1){
			*str+=z;
			K_O(str , z);
		}
	else if(indi == -1);
	else	
	{	str->insert(indi+1,z);
		K_O(str ,z);
	}
}
 

<pre name="code" class="cpp">void pfdcp(string et, string pf[5][5] , int alp[3][26] , string nct[]){
	//遍歷密文，每次兩個 
	for(int i = 0 ; i<et.length() ; i+=2){
		//將密文字母轉化為對應字母表的下標 
		int cti1 = (int)et[i];
		cti1-=97;
		int cti2 = (int)et[i+1];
		cti2-=97;

		//逆處理 
		int fline =alp[1][cti1],frow = alp[2][cti1];
		int sline = alp[1][cti2],srow = alp[2][cti2];
		if(fline == sline){//同行，還要判斷是否黏著 
			if(frow - srow == -1){
				nct[i] = pf[fline][(frow+3)%5];//這裡應該是frow-2+5，防止負數 
				nct[i+1] = pf[fline][(frow+4)%5];
			}
			else if (frow - srow == 1){
				nct[i] = pf[fline][(frow+2)%5];
				nct[i+1] = pf[fline][(frow+3)%5];
			}
			else{
				nct[i] = pf[fline][(frow+4)%5];
				nct[i+1] = pf[fline][(srow+4)%5];
			}
		}	
		else if(frow == srow){ //同列，也要判斷是否黏著 
			if(fline - sline == -1){
				nct[i] = pf[(fline+3)%5][frow];
				nct[i+1] = pf[(fline+4)%5][frow];
			}
			else if(fline - sline == 1){
				nct[i] = pf[(fline+2)%5][frow];
				nct[i+1] = pf[(fline+3)%5][frow];
			}
			else{
				nct[i] = pf[(fline+4)%5][frow];
				nct[i+1] = pf[(sline+4)%5][frow];
			}
		}
		else {//不同行列  
			nct[i] = pf[fline][srow];
			nct[i+1] = pf[sline][frow];
		 }
	}
}
 

<pre name="code" class="cpp">void pfecp(string ct, string pf[5][5] , int alp[3][26] , string eText[]){

	//遍歷明文，每次兩個 
	for(int i = 0 ; i<ct.length() ; i+=2){
		//將明文字母轉化為對應字母表的下標 
		int cti1 = (int)ct[i];
		cti1-=97;
		int cti2 = (int)ct[i+1];
		cti2-=97;
		//判斷是否為j，如果是則改為i 
		if(cti1 == 9)
			cti1-=1;
		else if(cti2 == 9)
			cti2-=1;
		//判斷屬於哪種情況 ,經過明文處理，只有1.同行，2.同列，3.都不同 
		int fline =alp[1][cti1],frow = alp[2][cti1];
		int sline = alp[1][cti2],srow = alp[2][cti2];
		if(fline == sline){//同行，還要判斷是否黏著 
			if(frow - srow == -1){
				eText[i] = pf[fline][(frow+2)%5];
				eText[i+1] = pf[fline][(frow+3)%5];
			}
			else if (frow - srow == 1){
				eText[i] = pf[fline][(frow+1)%5];
				eText[i+1] = pf[fline][(frow+2)%5];
			}
			else{
				eText[i] = pf[fline][(frow+1)%5];
				eText[i+1] = pf[fline][(srow+1)%5];
			}
		}	
		else if(frow == srow){ //同列，也要判斷是否黏著 
			if(fline - sline == -1){
				eText[i] = pf[(fline+2)%5][frow];
				eText[i+1] = pf[(fline+3)%5][frow];
			}
			else if(fline - sline == 1){
				eText[i] = pf[(fline+1)%5][frow];
				eText[i+1] = pf[(fline+2)%5][frow];
			}
			else{
				eText[i] = pf[(fline+1)%5][frow];
				eText[i+1] = pf[(sline+1)%5][frow];
			}
		}
		else {//不同行列  
			eText[i] = pf[fline][srow];
			eText[i+1] = pf[sline][frow];
		 }
	}
}