排序两个对应的数组 [英] Sorting two corresponding arrays

问题描述

我有这样的$ C $这里C，它有两个数组。它排序的改编[] ，从而使最高值将在指数0。现在第二个数组的 ARR1 [] 包含字符串，我想在code适用无论在哪里的改编[] 作出的 ARR1 [] 的变化。这样的改编[0] 将返回6，而 ARR1 [0] 将返回字符串D1。请注意如何D1是相同的索引在 6 ？排序后我想相同的价值观仍然有它们的字符串对应。

我将如何去这样做呢？

 的#include＆LT;＆iostream的GT;
＃包括LT＆;＆了iomanip GT;
＃包括LT＆;＆算法GT;
的#include＆lt;功能＆GT;
使用命名空间std;
主要（）{
INT ARR [5] = {4,1，3，6,2};串ARR1 [5] = {A1，B1，C1，D1，E1};的std ::排序（ARR，编曲+ 5，性病::更大＆LT; INT＆GT;（））;
COUT＆LT;＆LT;改编[0]＆下;＆下; ARR1 [0]＆下;＆下; ENDL;系统（暂停）;
}
 

解决方案

而不是数组进行排序，指数排序。即，你有

  INT ARR [5] = {4,1,3,6,2}
串ARR1 [5] = {A1，B1，C1，D1，E1};
 

和您

  INT指数[5] = {0,1,2,3,4};
 

现在你做一个排序指标比较，看起来像这样（只是和想法，你可能必须解决它一点点）

 类sort_indices
{
   私人的：
     INT * mparr;
   上市：
     sort_indices为（int *帕尔）：mparr（帕尔）{}
     布尔运算符（）（诠释我，诠释J）const的{返回mparr [1]  - ; mparr [J]。 }
}
 

现在你可以使用STL排序

 的std ::排序（指数，指数+ 5，sort_indices（ARR））;
 

当您完成后，指数阵列将是这样的：改编[指数[0] 是第一要素。同样地 ARR1 [指数[0] 是相应的一对。

这也是当你试图理清一个大的数据对象，你不需要在每一个交换四处移动的数据，仅仅是指数一个非常有用的技巧。

I have this code here that has two arrays. It sorts arr[], so that the highest value will be in index 0. Now the second array arr1[] contains strings, I'd like the code to apply whatever changes where made to arr[] to arr1[]. So that arr[0] would return 6, while arr1[0] would return the string "d1". Notice how "d1" was at the same index as 6? After sorting I'd like the same values to still have their string counterparts.

How would I go about doing this?

#include <iostream>
#include <iomanip>
#include <algorithm>
#include <functional>
using namespace std ;


main(){
int arr[ 5 ] = { 4, 1, 3, 6, 2 };

string arr1[ 5 ] = { "a1", "b1", "c1", "d1", "e1" };

std::sort( arr, arr + 5, std::greater< int >() );
cout << arr[0] << arr1[0] << endl;

system("pause");
}

解决方案

Rather than sort the arrays, sort the indices. I.e., you have

int arr[5]={4,1,3,6,2}
string arr1[5]={"a1","b1","c1","d1","e1"};

and you make

int indices[5]={0,1,2,3,4};

now you make a sort indices comparator that looks like this (just and idea, you'll probably have to fix it a little)

class sort_indices
{
   private:
     int* mparr;
   public:
     sort_indices(int* parr) : mparr(parr) {}
     bool operator()(int i, int j) const { return mparr[i]<mparr[j]; }
}

now you can use the stl sort

std::sort(indices, indices+5, sort_indices(arr));

when you're done, the indices array will be such that arr[indices[0]] is the first element. and likewise arr1[indices[0]] is the corresponding pair.

This is also a very useful trick when you're trying to sort a large data object, you don't need to move the data around at every swap, just the indices.

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