#include <iostream> #include <numeric> #include <vector> using matrix = std::vector<std::vector<int>>; int main() { matrix mtx{5, std::vector<int>(5)}; int sum = 0; for (const auto i : mtx) // can be avoided ? sum += std::accumulate(i.begin(), i.end(), 0, [](int a, int b){a > 0 ? a + b : a;}); } I want to use std::accumulate for ..
Category : accumulate
Let’s say I want to compute the cumulative product of the first k elements of an array. int arr[8] = {3, 5, 7, 4, 8, 9, 1, 2}; int k = 3; Which one is the best option? Option 1. Ordinary for loop int result = 1; for (size_t i = 0; i < k; ..
If I use the accumulate function in C++ like the below std::vector<int> v2{1, 2, 3, 4, 5}; int sum = 0; std::cout << std::accumulate(v2.begin(), v2.end()) It will simply sum all the numbers. But I wanted to calculate 1-2+3-4+5 I was thinking of some way to accumulate 1,3,5 and 2,4 separately and then do it But ..
I have a function which should accumulate all the values in an unordered map: int sum_val(std::unordered_map<char, int> vm){ auto addition = [](int a, std::unordered_map<char, int>::iterator b){ return a + b->second; }; return std::accumulate(vm.begin(), vm.end(), 0, addition); } However, when I try to compile this, I get the following error: error: no matching function for call ..
I would like to know if there is anyway to perform Sum of a vector till specific index using accumulate(). Example vector<int> v ={1,2,3,4,5,6}; int sum = accumulate(v.begin(), till_index_4, 0); All examples i found says accumulate(v.begin(), v.end(), 0); I tried with iterator also but my code is not compiled. Please let me if there is ..
I’ve been working on a program where I need to be able to sum rows in a two-dimensional array whose number of columns are variable. I should also add that the rows are "split" into two parts (part A, and part B) whose sizes depend on user input. I can obviously sum a row just ..
Just for fun, I am trying to calculate a file’s mean value of data bytes, essentially replicating a feature available in an already existing tool (ent). Basically, it is simply the result of summing all the bytes of a file and dividing by the file length. If the data are close to random, this should ..
I couldnt find any solution, so Im posting a new topic. I have to use accumulate with a const function as a parameter (doing some practice for a test): get_skills() – returns a list of skills and is defined as: const vector<string>& get_skills() const; I have to return a sum of the lengths of all ..
When i am coding the code below, i am getting a negative sum (-294967296). #include<iostream> #include<vector> #include<numeric> using namespace std; int main() { vector<long long int> v={1000000000 , 1000000000 , 1000000000 , 1000000000}; cout<<"Sum of all the elements are:"<<endl; cout<<accumulate(v.begin(),v.end(),0); } but when i am coding the code below i am getting a positive sum ..
The result of the following code is very surprising to me. Why does using accumulate produce such a large error? I know that because it is single precisions, it will have a round-off error but when using reduce without any policy (single precision), this round-off error is not so significant! In fact, round-off errors is ..
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