public static void insertion(int[] a) {
  for(int j = 1; i < a.length; j++) {
    int i = j - 1;
    int t = a[j];
    while(i >= 0 && t < a[i]) {
      a[i+1] = a[i];
      j--;
    }
    a[i+1] = t;
  }
}