add rough realisation of the first algo. Doesn't path tests

Author: koss-null

py3/median/link

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+https://leetcode.com/problems/median-of-two-sorted-arrays/

py3/median/median.py

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+class Solution:
+    def single_place(self, nums, num):
+        """returns on which place >= num starts and how many same items"""
+        lf, rg = 0, len(nums) - 1
+        md = (lf + rg) // 2
+        while lf <= rg and nums[md] != num:
+            if nums[md] <= num:
+                lf = md + 1
+            else:
+                rg = md - 1
+            md = (lf + rg) // 2
+
+        if nums[md] == num:
+            left_step, right_step = 1 >> 11, 1 >> 11
+            lf_sum, rg_sum = 0, 0
+            while left_step and right_step:
+                if md - left_step - lf_sum < 0 or nums[md - left_step - lf_sum] != num:
+                    left_step <<= 1
+                else:
+                    lf_sum += left_step
+
+                if md + right_step + rg_sum  >= len(nums) or nums[md + right_step + rg_sum] != num:
+                    right_step <<= 1
+                else:
+                    rg_sum += right_step
+
+            return [md - lf_sum, rg_sum + lf_sum + 1]
+        return [lf, 0]
+
+    def place(self, nums1, nums2, num):
+        """returns the leftmost and the rightmost place of the element from nums1 in merged list"""
+        place1, place2 = self.single_place(nums1, num), self.single_place(nums2, num)
+        return [place1[0] + place2[0] + 2, place1[1] + place2[1]]
+
+    def find_place(self, nums, other_nums, desired_place):
+        lf, rg = 0, len(nums) - 1
+        md = (lf + rg) // 2
+        p = self.place(nums, other_nums, nums[md])
+        while lf <= rg and not (p[0] <= desired_place <= p[0] + p[1]):
+            if p[0] > desired_place:
+                rg = md - 1
+            else:
+                lf = md + 1
+            md = (lf + rg) // 2
+            p = self.place(nums, other_nums, nums[md])
+        return p
+
+    def findMedianSortedArrays(self, nums1, nums2, desired_place=None, need_two=None):
+        if desired_place is None:
+            desired_place = int((len(nums1) + len(nums2)) / 2.0 + 0.5)
+        if need_two is None:
+            need_two = (len(nums1) + len(nums2)) % 2 == 0
+
+        p = self.find_place(nums1, nums2, desired_place)
+        if p[0] <= desired_place < p[0] + p[1]:
+            second = nums1[p[0] - 1]
+            if need_two:
+                second = self.findMedianSortedArrays(nums1, nums2, desired_place=desired_place+1, need_two=False)
+            return (nums1[p[0] - 1] + second) / 2.
+
+        p = self.find_place(nums2, nums1, desired_place)
+        if p[0] <= desired_place < p[0] + p[1]:
+            second = nums2[p[0] - 1]
+            if need_two:
+                second = self.findMedianSortedArrays(nums1, nums2, desired_place=desired_place+1, need_two=False)
+            return (nums2[p[0] - 1] + second) / 2.
+
+        print("Something went wrong")
+        return -1
+
+
+def main():
+    a = list(map(int, input().split()))
+    b = list(map(int, input().split()))
+    print(Solution().findMedianSortedArrays(a, b))
+
+
+if __name__ == "__main__":
+    main()

py3/median/test/test1

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+{
+"input": "1 3\n2",
+"output": "2.00000"
+}

py3/median/test/test2

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+{
+"input": "1 2\n3 4",
+"output": "2.5"
+}