docs: public static long[] insertEntry(long[] a, int idx, long val) {
          long[] b = new long[a.length + 1];
          for (int i = 0; i < b.length; i++) {
              if (i < idx) {
                  b[i] = a[i];
              } else if (i == idx) {
                  b[idx] = val;
              } else {
                  b[i] = a[i - 1];
              }
          }
          return b;
      }