File size: 1,190 Bytes
bff4ec7 | 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 | /*@ Import Lean
import Algorithms.majority_element.lean.helper_lib
open scoped SimpleC
*/
/*@ Extern Coq (IsMajorityElement : Z -> list Z -> Prop) */
/*@ Extern Coq (MajorityOnReduced : Z -> Z -> Z -> list Z -> Prop) */
int majorityElement(int* nums, int numsSize)
/*@ With (l : list Z)
Require exists x, IsMajorityElement(x,l) && 1 <= numsSize && numsSize <= 50000 && Zlength(l) == numsSize && IntArray::full(nums, numsSize, l)
Ensure IsMajorityElement(__return, l) && IntArray::full(nums, numsSize, l)
*/
{
int vote = 0;
int candidate = 0;
/*@ Inv Assert
exists x l1 l2,
nums == nums@pre && numsSize == numsSize@pre &&
l == app(l1, l2) &&
i == Zlength(l1) &&
0 <= i && i <= numsSize &&
1 <= numsSize && numsSize <= 50000 &&
0 <= vote && vote <= i &&
IsMajorityElement(x, l) &&
MajorityOnReduced(x, candidate, vote, l2) &&
IntArray::full(nums, numsSize, l)
*/
for (int i = 0; i < numsSize; i++) {
if (vote == 0) {
candidate = nums[i];
}
vote += (nums[i] == candidate) ? 1 : -1;
}
return candidate;
} |