4.cpp

/**
 *    author:   vulkan
 *    created:  07.03.2020 03:33:09 PM
**/
#include <bits/stdc++.h>

using namespace std;

double median(int left, int right, int size) {
    if (size % 2) {
        return left;
    } else {
        return double(left + right) / 2;
    }
}

double findMedianSortedArrays(vector<int> &nums1, vector<int> &nums2) {
    int n = nums1.size(), m = nums2.size();
    if (n == 0) {
        return (m == 1) ? nums2[0] : median(nums2[(m - 1) / 2], nums2[(m - 1) / 2 + 1], m);
    } else if (m == 0) {
        return (n == 1) ? nums1[0] : median(nums1[(n - 1) / 2], nums1[(n - 1) / 2 + 1], n);
    }

    if (n > m) {
        swap(nums1, nums2);
        swap(n, m);
    }

    int l = 0, h = n;
    while (l <= h) {
        int i = (l + h) / 2;
        int j = (n + m + 1) / 2 - i;

        if (i > 0 and j > 0) {
            int left = max(nums1[i - 1], nums2[j - 1]);
            int right = (i < n) ? min(nums1[i], nums2[j]) : nums2[j];

            if (left > right) {
                if (left == nums1[i - 1]) {
                    h = i;
                } else {
                    l = i + 1;
                }
            } else {
                return median(left, right, n + m);
            }
        } else if (i == 0) {
            int right = (j < m) ? min(nums1[0], nums2[j]) : nums1[0];
            if (nums2[j - 1] > right) {
                l = i + 1;
            } else {
                return median(nums2[j - 1], right, n + m);
            }
        } else if (j == 0) {
            if (nums1[i - 1] > nums2[0]) {
                h = i;
            } else {
                return median(nums1[i - 1], nums2[0], n + m);
            }
        }
    }

    return -1;
}


int main(int argc, char const *argv[]) {
    int n, m;
    cin >> n >> m;
    vector<int> nums1(n), nums2(m);

    for (int i = 0; i < n; ++i) {
        cin >> nums1[i];
    }

    for (int i = 0; i < m; ++i) {
        cin >> nums2[i];
    }

    double ans = findMedianSortedArrays(nums1, nums2);
    printf("%.1f\n", ans);

    return 0;
}