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#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
typedef struct {
long a;
long b;
long r;
} arg_t;
void * f(void * arg_) {
arg_t * arg = (arg_t *)arg_;
long a = arg->a, b = arg->b;
if (b - a == 1) {
arg->r = a;
} else {
long c = (a + b) / 2;
arg_t cargs[2] = { { a, c, 0 }, { c, b, 0 } };
pthread_t tid;
int r = pthread_create(&tid, 0, f, cargs);
assert(r == 0);
f(cargs + 1);
pthread_join(tid, 0);
arg->r = cargs[0].r + cargs[1].r;
}
return 0;
}
int main(int argc, char ** argv) {
long nthreads = (argc > 1 ? atol(argv[1]) : 100);
arg_t arg[1] = { { 0, nthreads, 0 } };
pthread_t tid;
int r = pthread_create(&tid, 0, f, arg);
assert(r == 0);
pthread_join(tid, 0);
if (arg->r == (nthreads - 1) * nthreads / 2) {
printf("OK\n");
return 0;
} else {
printf("NG\n");
return 1;
}
}
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