Simple Python Solution using Heap
\nclass Solution:\n    def minimumSum(self, num: int) -> int:\n        heap, n = [], num\n        while n > 0: # Push all digits of num into heap\n            h
```\nclass Solution:\n    def minimumSum(self, num: int) -> int:\n        heap, n = [], num\n        while n > 0: # Push all digits of num into heap\n            heappush(heap,  n % 10)\n            n = n // 10\n        nums1 = nums2 = 0\n        while len(heap) > 0: # Use smallest digits to construct each number\n            v1 = heappop(heap)\n            nums1 = nums1 * 10 + v1\n            if len(heap) > 0:\n                v2 = heappop(heap)\n                nums2 = nums2 * 10 + v2\n        return nums1 + nums2\n```
['Heap (Priority Queue)', 'Python', 'Python3']