Datasets:
File size: 2,138 Bytes
c62beea | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 | use vstd::prelude::*;
fn main() {}
verus!{
fn f1_split_and_append(list: &Vec<i32>, n: usize) -> (new_list: Vec<i32>)
requires
list@.len() > 0,
0 < n < list@.len(),
{
let mut new_list = Vec::new();
let mut index = n;
while index < list.len()
{
new_list.push(list[index]);
index += 1;
}
let mut index = 0;
while index < n
{
new_list.push(list[index]);
index += 1;
}
new_list
}
pub open spec fn count_frequency_rcr(seq: Seq<i32>, key: i32) -> int
decreases seq.len(),
{
if seq.len() == 0 {
0
} else {
count_frequency_rcr(seq.drop_last(), key) + if (seq.last() == key) {
1 as int
} else {
0 as int
}
}
}
fn f2_count_frequency(arr: &Vec<i32>, key: i32) -> (frequency: usize)
{
let mut index = 0;
let mut counter = 0;
while index < arr.len()
{
if (arr[index] == key) {
counter += 1;
}
index += 1;
}
counter
}
fn f2_remove_duplicates(arr: &Vec<i32>) -> (unique_arr: Vec<i32>)
{
let mut unique_arr: Vec<i32> = Vec::new();
let input_len = arr.len();
let mut index = 0;
while index < arr.len()
{
if f2_count_frequency(&arr, arr[index]) == 1 {
unique_arr.push(arr[index]);
}
index += 1;
}
unique_arr
}
spec fn step1(__hp0: Seq<i32>, __hp1: usize, outp: Seq<i32>) -> bool {
(outp == __hp0.subrange(__hp1 as int, __hp0.len() as int).add(__hp0.subrange(0, __hp1 as int)))
}
spec fn step2(inp: Seq<i32>, p2_key: i32, outp: usize) -> bool {
(count_frequency_rcr(inp, p2_key) == outp)
}
fn chain_driver(list: &Vec<i32>, n: usize, p2_key: i32) -> (r_final: usize)
requires
list@.len() > 0,
0 < n < list@.len(),
ensures
exists|v1: Seq<i32>| #[trigger] step1(list@, n, v1) && step2(v1, p2_key, r_final),
{
let x1 = f1_split_and_append(list, n);
let x2 = f2_count_frequency(&x1, p2_key);
proof {
assert(step1(list@, n, x1@));
assert(step2(x1@, p2_key, x2));
}
x2
}
} // verus!
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