Function encode 

pub fn encode(xs: &[usize]) -> usize

Returns the value of a combination.

The returned value can be decoded with decode to get back xs.

let k = xs.len();
let n = encode(xs);
assert_eq!(decode(n, k), xs);

Panics

Panics in debug mode if xs is not increasing.

Examples

assert_eq!(encode(&[0, 1, 2]), 0);
assert_eq!(encode(&[0, 1, 3]), 1);
assert_eq!(encode(&[0, 2, 3]), 2);
assert_eq!(encode(&[1, 2, 3]), 3);
assert_eq!(encode(&[0, 1, 4]), 4);
assert_eq!(encode(&[0, 2, 4]), 5);