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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 | use vstd::prelude::*;
fn main() {}
verus!{
spec fn f1_sum_to(arr: Seq<i64>) -> int
decreases arr.len(),
{
if arr.len() == 0 {
0
} else {
f1_sum_to(arr.drop_last()) + arr.last()
}
}
fn f1_sum_range_list(arr: &Vec<i64>, start: usize, end: usize) -> (sum: i128)
requires
0 <= start <= end,
start <= end < arr.len(),
{
let mut index = start;
let mut sum = 0i128;
let _end = end + 1;
while index < _end
{
sum = sum + arr[index] as i128;
index += 1;
}
sum
}
spec fn step1(__hp0: Seq<i64>, __hp1: usize, __hp2: usize, outp: i128) -> bool {
(f1_sum_to(__hp0.subrange(__hp1 as int, __hp2 + 1 as int)) == outp)
}
fn chain_driver(arr: &Vec<i64>, start: usize, end: usize) -> (r_final: i128)
requires
0 <= start <= end,
start <= end < arr.len(),
ensures
step1(arr@, start, end, r_final),
{
let x1 = f1_sum_range_list(arr, start, end);
proof {
assert(step1(arr@, start, end, x1));
}
x1
}
} // verus!
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