[作业自己做系列] 有大佬吗？ 如何生成n个[a1，a2]范围内，和为b的随机数列？

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <stdio.h>
#include <sys/time.h>
#include <random>
using namespace std;

long getTimeNs()
{
struct timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);

return ts.tv_sec * 1000000000 + ts.tv_nsec;
}
default_random_engine e;

int a[100000];
int main()
{
e.seed(getTimeNs());
int a1, a2, b, n;
cin >> a1 >> a2 >> b >> n;
uniform_int_distribution<int> N(1, 30);

for (int i = 1; i <= n; i++)
{
int l = max(a1, b - (n - i) * a2);
int r = min(a2, b - (n - i) * a1);
uniform_int_distribution<int> N(l, r);

a[i] = N(e);
b -= a[i];
}

for (int i = 1; i <= n; i++)
cout << a[i] << " ";
}