Method backtrack

46-permutations.rs:22–33

(path: &mut Vec<i32>, ans: &mut Vec<Vec<i32>>, begin: usize)

    }

    fn backtrack(path: &mut Vec<i32>, ans: &mut Vec<Vec<i32>>, begin: usize) {
        if begin == path.len() {
            ans.push(path.to_vec());
            return;
        }

        for i in begin..path.len() {
            path.swap(i, begin);
            Self::backtrack(path, ans, begin + 1);
            path.swap(i, begin);
        }
    }
}

fn main() {