public int[] shiftLeft(int[] nums) {
  int[] a = new int[nums.length];
  if (nums.length > 0) {
    for (int i = 1; i < nums.length; i++) {
      a[i-1] = nums[i];
    }
    a[nums.length-1] = nums[0];
  }
  return a;
}

public int[] shiftLeft(int[] nums) {
  int[] a = new int[nums.length];
  for (int i = 0; i < nums.length; i++) {
    int fromIdx = (i+1) % nums.length;
    int toIdx = i;
    a[toIdx] = nums[fromIdx];
  }
  return a;
}