| /*@ Import Lean | |
| import Algorithms.house_robber.lean.helper_lib | |
| open scoped SimpleC | |
| */ | |
| /*@ Extern Coq | |
| (RobPrefixValue : list Z -> Z -> Z -> Prop) | |
| (RobPrefixOpt : list Z -> Z -> Z -> Prop) | |
| (HouseRobberDPState : list Z -> Z -> Z -> Z -> Prop) | |
| (HouseRobberAnswer : list Z -> Z -> Prop) | |
| */ | |
| int rob(int *nums, int n) | |
| /*@ With (l : list Z) | |
| Require | |
| 0 <= n && n <= 100000 && | |
| Zlength(l) == n && | |
| IntArray::full(nums, n, l) && | |
| (forall (k : Z), (0 <= k && k < n) => (0 <= l[k] && l[k] <= 10000)) | |
| Ensure | |
| HouseRobberAnswer(l, __return) && | |
| 0 <= __return && __return <= 1000000000 && | |
| IntArray::full(nums, n, l) | |
| */ | |
| { | |
| int prev2 = 0; | |
| int prev1 = 0; | |
| /*@ Inv Assert | |
| nums == nums@pre && n == n@pre && | |
| 0 <= n@pre && n@pre <= 100000 && | |
| Zlength(l) == n@pre && | |
| IntArray::full(nums, n@pre, l) && | |
| (forall (k : Z), (0 <= k && k < n@pre) => (0 <= l[k] && l[k] <= 10000)) && | |
| 0 <= i && i <= n@pre && | |
| 0 <= prev2 && prev2 <= 1000000000 && | |
| 0 <= prev1 && prev1 <= 1000000000 && | |
| HouseRobberDPState(l, i, prev2, prev1) | |
| */ | |
| for (int i = 0; i < n; ++i) { | |
| int take = prev2 + nums[i]; | |
| int skip = prev1; | |
| int cur; | |
| if (take > skip) { | |
| cur = take; | |
| } else { | |
| cur = skip; | |
| } | |
| /*@ Assert | |
| nums == nums@pre && n == n@pre && | |
| 0 <= n@pre && n@pre <= 100000 && | |
| Zlength(l) == n@pre && | |
| IntArray::full(nums, n@pre, l) && | |
| (forall (k : Z), (0 <= k && k < n@pre) => (0 <= l[k] && l[k] <= 10000)) && | |
| 0 <= i && i < n@pre && | |
| take == prev2 + l[i] && | |
| skip == prev1 && | |
| 0 <= prev2 && prev2 <= 1000000000 && | |
| 0 <= prev1 && prev1 <= 1000000000 && | |
| 0 <= cur && cur <= 1000000000 && | |
| HouseRobberDPState(l, i + 1, prev1, cur) | |
| */ | |
| prev2 = prev1; | |
| prev1 = cur; | |
| } | |
| return prev1; | |
| } | |