Weighted Random Sampling With Replacement 

Select k items from n with replacement, based on weights w[n]. Populate dest from src. Here, k=n. 

double sum_w = 0.0;

for(i = 0; i < n; ++i) {

  sum_w += w[i];

}

int i, j;

for (j = 0; j < n; ++j){

  double u = random*sum_w;

  for(i = 0; i < n; ++i) {

    u -= w[i];

    if (u < 0) {break;}

  }

  dest[j]=src[i];

}