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#include "Thread.h"
#include <iostream>
const long long N = 1e9;
int main(int argc, char **argv) {
int thread_number;
if (argc == 1) {
thread_number = 1;
} else if (argc == 2) {
thread_number = std::atoi(argv[1]);
if (thread_number <= 0) {
std::cerr << "Argument must be a positive integer.\n";
return -1;
}
} else {
std::cerr << "Too many arguments.\n";
return -1;
}
std::cout << "Use " << thread_number << " threads to calculate sum of 1-" << N
<< ".\n";
if (thread_number == 1) {
long long sum = 0;
for (long long i = 1; i <= 1e9; i++) {
sum += i;
}
std::cout << "Sum of 1-" << N << " is " << sum << '\n';
} else {
std::vector<cru::Thread> threads(thread_number);
std::vector<long long> partial_sum(thread_number);
long long step = N / thread_number;
for (int i = 0; i < thread_number; i++) {
long long start = step * i;
long long end = step * (i + 1);
long long &ps = partial_sum[i];
if (i == thread_number - 1) {
threads[i] = cru::Thread([&ps, start] {
long long sum = 0;
for (long long j = start; j <= N; j++) {
sum += j;
}
ps = sum;
});
} else {
threads[i] = cru::Thread([&ps, start, end] {
long long sum = 0;
for (int j = start; j < end; j++) {
sum += j;
}
ps = sum;
});
}
}
for (auto &thread : threads) {
thread.Join();
}
long long sum = 0;
for (auto ps : partial_sum) {
sum += ps;
}
std::cout << "Sum of 1-" << N << " is " << sum << '\n';
}
return 0;
}
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