Solution.py

class Solution:
    def findRadius(self, houses: List[int], heaters: List[int]) -> int:
        houses.sort()
        heaters.sort()

        def check(r):
            m, n = len(houses), len(heaters)
            i = j = 0
            while i < m:
                if j >= n:
                    return False
                mi = heaters[j] - r
                mx = heaters[j] + r
                if houses[i] < mi:
                    return False
                if houses[i] > mx:
                    j += 1
                else:
                    i += 1
            return True

        left, right = 0, int(1e9)
        while left < right:
            mid = (left + right) >> 1
            if check(mid):
                right = mid
            else:
                left = mid + 1
        return left