我基本上要创建的字符串，它由三个操作符号（例如： + - * 或 ++ / 或 +++ ）。这些字符串中的每一个应该被推入矢量＆lt;串GT; opPermutations 这是我的code到目前为止：

I basically want to create strings that consist of three operation symbols (eg: +-* or ++/ or +++). Each one of these strings should be pushed into vector <string> opPermutations This is my code so far:

 // Set up permutations for operators

string operatorBank[4] = {"+","-","*","/"};

 do {

    string currentPerm = operatorBank[0] + operatorBank[1] + operatorBank[2] + operatorBank[3];

    this -> opPermutations.push_back(currentPerm);

} while ( std::next_permutation(operatorBank, operatorBank + 4) );

这被推入载体（字符串）的排列是：

The permutations that are pushed into the vector (as strings) are:

+-*/                                                                                                                                                                                           
+-/*                                                                                                                                                                                           
+/*-                                                                                                                                                                                           
+/-*                                                                                                                                                                                           
-*+/                                                                                                                                                                                           
-*/+                                                                                                                                                                                           
-+*/                                                                                                                                                                                           
-+/*                                                                                                                                                                                           
-/*+                                                                                                                                                                                           
-/+*                                                                                                                                                                                           
/*+-                                                                                                                                                                                           
/*-+                                                                                                                                                                                           
/+*-                                                                                                                                                                                           
/+-*                                                                                                                                                                                           
/-*+                                                                                                                                                                                           
/-+*  

我要的不过是让我的排列存在这样的：

What I want however is to have my permutations exist like this:

我希望它被组织成这样的：

I want it to be organized as such:

+++
---
*** 
/// 
/*/
+-+
++*
**/

etc...

我怎样才能做到这一点？

How can I achieve this?

推荐答案

使用递归来打印你的要求。它适应店内置换字符串中的载体应该是微不足道的。我不是一个C ++程序员，所以有可能是更好的方法来做到这一点在C ++中。但这里的主要思想是使用递归。

Using the recursion to print what you asked. Adapting it to store permutation string in vectors should be trivial. I am not a c++ programmer,so there may be better way to do it in C++. but the main idea here is to use recursion.

    #include <iostream>
    #include <string>
    #include <math.h>
    #include <stdio.h>
    #include <stdlib.h>
    using namespace std;

    void displayPermutation(string permutation[], int length){
        int i;
        for (i=0;i<length;i++){
            cout<<permutation[i];
        }
        cout << endl;
    }

    void getPermutations(string operatorBank[], int operatorCount, 
            string permutation[],int permutationLength, int curIndex){
        int i;
        //stop recursion condition
        if(curIndex == permutationLength){
            displayPermutation(permutation,permutationLength);
        }
        else{
            for(i = 0; i < operatorCount; i++){
                permutation[curIndex] = operatorBank[i];
                getPermutations(operatorBank,operatorCount,permutation,
                    permutationLength,curIndex+1);
            }
        }
    }

    int main ()
   {
       int operatorCount = 4;
       int permutationLength = 3;
       string operatorBank[] = {"+","-","*","/"};
       string permutation[] = {"","","",""}; //empty string
       int curIndex = 0;
       getPermutations(operatorBank,operatorCount,permutation,
                                   permutationLength,curIndex);
       return 0;
   }

输出：

   +++
   ++-
   ++*
   ++/
   +-+
   +--
   +-*
   +-/
   +*+
   +*-
   +**
   +*/
   +/+
   +/-
   +/*
   +//
   .
   .
  and so on.