Find the elements of an array based on minimum sum

Question

I've written a loop in C++ to give me 6 random numbers and store them in an array. What I would like to do is to sum the elements of the array until I get a value larger than a number, "x", but I would like to do this without necessarily adding all the elements. The objective is to find the first elements which sum to the value of x.

For example, array is [1,2,3,4,5,6], and x = 6, so what I would be looking for are the elements [1,2,3].

I've looked at the standard library and have tried using the sum function from "valarray" but this just gives the sum of all the elements. Any ideas on how to code this successfully would be greatly appreciated.

Answer 1

Write a functor that does the addition.

#include <algorithm>
struct SumToo
{
     SumToo(int val):m_val(val),m_sum(0) {}
     int m_val;
     int m_sum;

     bool operator()(int next)
     {
         m_sum += next;
         return m_sum >= m_val;
     }
 };

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

       int* find = std::find_if(data,data+6,SumToo(6));
 }