C ++优雅的解决方案分区问题 [英] C++ Elegant solution to partition problem

问题描述

我想在
STL中看到最优雅的STL像分区算法的扩展：

 给定一个ints的向量，分割向量使得正整数出现
到负整数的前面
 AND 
返回一个映射< int，int>其中map [i] = j意味着索引i的整数现在为j。 
 

显然，第一部分（没有第二个要求）是

  partititon（vec.begin（），vec.end（），IsEven）
   
 
我没有看到这样做的方法，没有实际重新实现分区和构建
映射。 
解决方案
将int的向量复制到如下的向量中：
  struct ValIdx 
 {
 int val; 
 size_t idx; 
}; 
 
使用适当的函子进行分区，然后迭代结果，将ints复制回来并构建映射。 
 
I would like to see the most elegant STL like extension to the partition algorithm in the
STL:
given a vector of ints, partition the vector so that the positive integers appear
to the front of the negative integers
AND
return a map<int, int> where map[i]=j means that integer at index i is now at j.
Obviously the first part (without the second requirement) is something like
partititon(vec.begin(), vec.end(), IsEven)
I can't see a way to do this without actually reimplementing partition and building the
map along the way. 
解决方案
Copy your vector of ints into a vector of something like:
struct ValIdx
{
    int val;
    size_t idx;
};
Partition with an appropriate functor, then iterate over the result copying the ints back out and building your map.

                        
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