fn biggerIsGreater(w: &str) -> String {
    let length = w.len();
    let mut temp = w.chars().collect::<Vec<char>>();
    let mut i = None; //
    let mut idx: Option<usize> = None;
    let mut smallest = 'z';

    for a in (0..length - 1).rev() {
        if temp[a] < temp[a + 1] {
            i = Some(a);
            break;
    }
}
    if let Some(i) = i {
    let mut j = i + 1;
    for k in i + 1..length {
    if temp[k] > temp[i] && (j == i + 1 || temp[k] < temp[j]) {
        idx = Some(k);
    }
}
        if let Some(j) = idx {
            temp.swap(i, j);
            temp[i + 1..].sort();
        }
        temp.iter().collect()
    } else {
        "no answer".into()
    }
}

sub sorted_descending {
    my $arr = shift;
    for (my $i = 0; $i < scalar(@$arr) - 1; $i++) {
        return 0 if ($arr->[$i] lt $arr->[$i + 1]);
    }
    return 1;
}

sub biggerIsGreater {
    my $w = shift;
    
    my @arr = split("", $w);
    my $max = $arr[1];
    my $ind = 0;
    my @res;
    if (sorted_descending(\@arr)) {
        return "no answer";
    } else {
        my $k = $#arr - 1;
        while ($k >= 0 && $arr[$k] ge $arr[$k + 1]) {
            $k--;
        }
        
        my $l = $#arr; 
        while ($arr[$l] le $arr[$k]) {
            $l--;
        }
        
        ($arr[$k], $arr[$l]) = ($arr[$l], $arr[$k]);
        push(@res, @arr[0..$k], reverse(splice(@arr, $k+1, $#arr)));
        
        return join("", @res);
    }
}

def find_smallest_char_larger(s, idx):
    char_compare = s[idx]
    sorted_chars = sorted(s[(idx + 1):])
    for char in sorted_chars:
        if char > char_compare:
            i = s.index(char, idx)
            return i
    return None
    
def biggerIsGreater(w):
    # Write your code here
    w_list = list(w)
    
    for idx in reversed(range(0, len(w) - 1)):
        char_i_to_swap = find_smallest_char_larger(w_list, idx)
        if char_i_to_swap is not None:
            w_list[char_i_to_swap], w_list[idx] = w_list[idx], w_list[char_i_to_swap]
            w_list[(idx + 1):] = sorted(w_list[(idx + 1):])
            return ''.join(w_list)
    
    return 'no answer'