004 solved.

0004-Median-of-Two-Sorted-Arrays/cpp-0004/CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.14)
+project(cpp_0004)
+
+set(CMAKE_CXX_STANDARD 14)
+
+add_executable(cpp_0004 main.cpp)

0004-Median-of-Two-Sorted-Arrays/cpp-0004/main.cpp

@@ -0,0 +1,80 @@
+/// Source : https://leetcode.com/problems/median-of-two-sorted-arrays/
+/// Author : liuyubobobo
+/// Time   : 2019-06-13
+
+#include <iostream>
+#include <vector>
+#include <cassert>
+
+using namespace std;
+
+
+/// Binary Search
+/// Time Complexity: O(log(min(n, m)))
+/// Space Complexity: O(1)
+class Solution {
+public:
+    double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2) {
+
+        if(nums1.size() > nums2.size()) swap(nums1, nums2);
+
+        int n = nums1.size(), m = nums2.size();
+        if(n == 0) return m % 2 ? nums2[m / 2] : (nums2[m / 2 - 1] + nums2[m / 2]) / 2.0;
+        int half = (n + m) / 2;
+
+        int l = 0, r = n;
+        while(l <= r){
+            int mid = (l + r) / 2;
+
+            int i1 = mid, i2 = half - i1;
+
+            int leftMax = i1 == 0 ? nums2[i2 - 1] :
+                          i2 == 0 ? nums1[i1 - 1] : max(nums1[i1 - 1], nums2[i2 - 1]);
+            int rightMin = i1 == n ? nums2[i2] :
+                           i2 == m ? nums1[i1] : min(nums1[i1], nums2[i2]);
+
+            if(leftMax <= rightMin){
+                if((n + m) % 2 == 1)
+                    return rightMin;
+                else{
+                    int nums1Left = i1 == 0 ? INT_MIN :
+                                    i1 == 1 ? nums1[i1 - 1] : max(nums1[i1 - 1], nums1[i1 - 2]);
+                    int nums1Right = i1 == n ? INT_MAX :
+                                     i1 == n - 1 ? nums1[i1] : min(nums1[i1], nums1[i1 + 1]);
+                    int nums2Left = i2 == 0 ? INT_MIN :
+                                    i2 == 1 ? nums2[i2 - 1] : max(nums2[i2 - 1], nums2[i2 - 2]);
+                    int nums2Right = i2 == m ? INT_MAX :
+                                     i2 == m - 1 ? nums2[i2] : min(nums2[i2], nums2[i2 + 1]);
+                    return (max(nums1Left, nums2Left) + min(nums1Right, nums2Right)) / 2.0;
+                }
+            }
+            else if(nums1[i1] == rightMin)
+                l = mid + 1;
+            else
+                r = mid - 1;
+        }
+        assert(false);
+        return -1;
+    }
+};
+
+
+int main() {
+
+    vector<int> nums11 = {1, 3};
+    vector<int> nums12 = {2};
+    cout << Solution().findMedianSortedArrays(nums11, nums12) << endl;
+    // 2
+
+    vector<int> nums21 = {1, 2};
+    vector<int> nums22 = {3, 4};
+    cout << Solution().findMedianSortedArrays(nums21, nums22) << endl;
+    // 2.5
+
+    vector<int> nums31 = {};
+    vector<int> nums32 = {1};
+    cout << Solution().findMedianSortedArrays(nums31, nums32) << endl;
+    // 1
+
+    return 0;
+}

readme.md

@@ -50,7 +50,8 @@ email: [[email protected]](mailto:[email protected])
 | --- | --- | :---: | :--- | :--- | :--- |
 | 001 | [Two Sum](https://leetcode.com/problems/two-sum/description/) | [solution](https://leetcode.com/problems/two-sum/solution/) | [C++](0001-Two-Sum/cpp-0001/) | [Java](0001-Two-Sum/java-0001/src/) | |
 | 002 | [Add Two Numbers](https://leetcode.com/problems/add-two-numbers/description/) | [solution](https://leetcode.com/problems/add-two-numbers/solution/) | [C++](0002-Add-Two-Numbers/cpp-0002/) | | |
-| 003 | [Longest-Substring-Without-Repeating-Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/description/) | [solution](https://leetcode.com/problems/longest-substring-without-repeating-characters/solution/) | [C++](0003-Longest-Substring-Without-Repeating-Characters/cpp-0003/) | [Java](0003-Longest-Substring-Without-Repeating-Characters/java-0003/src/) | |
+| 003 | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/description/) | [solution](https://leetcode.com/problems/longest-substring-without-repeating-characters/solution/) | [C++](0003-Longest-Substring-Without-Repeating-Characters/cpp-0003/) | [Java](0003-Longest-Substring-Without-Repeating-Characters/java-0003/src/) | |
+| 004 | [Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays/) | [solution](https://leetcode.com/problems/median-of-two-sorted-arrays/solution/) | [C++](0004-Median-of-Two-Sorted-Arrays/cpp-0004/) | | |
 | | | | | | |
 | 007 | [Reverse Integer](https://leetcode.com/problems/reverse-integer/description/) | [solution](https://leetcode.com/problems/reverse-integer/solution/) | [C++](0007-Reverse-Integer/cpp-0007/) | | |
 | | | | | | |