Программирование с++ как решить эту задачу?

#include <iostream>
#include <random>
#include <iomanip>
using namespace std;
void fill_rand_int(int* v, const size_t n, int l, int r) {
if (r < l) swap(l, r);
uniform_int_distribution<> uid(l, r);
random_device rd;
mt19937 gen(rd());
for (auto i = 0U; i < n; ++i) v[i] = uid(gen);
}
void show(int* v, const size_t n, const streamsize w) {
for (auto i = 0U; i < n; ++i) cout << setw(w) << v[i];
cout.put('\n');
}
int sum(int* v, const size_t n) {
auto s = 0;
for (auto i = 0U; i < n; ++i) s += v[i];
return s;
}
int main() {
const auto rank = 4U;
const auto left = 1;
const auto right = 5;
const auto width = 4U;
int matrix[rank][rank];
for (auto& row : matrix) fill_rand_int(row, rank, left, right);
for (auto& row : matrix) show(row, rank, width);
cout.put('\n');
for (auto i = 0U; i < rank; ++i) matrix[i][i] = sum(matrix[i], rank);
for (auto& row : matrix) show(row, rank, width);
cout.put('\n');
cin.get();
}