added median of two sorted arrays cpp

Author: Luke-zhang-04

Hard/Median_of_Two_Sorted_Arrays/Median_of_Two_Sorted_Arrays.cpp

@@ -0,0 +1,56 @@
+#include <vector>
+
+// Runtime: 20 ms, faster than 72.52% of C++ online submissions for Median of Two Sorted Arrays.
+// Memory Usage: 10.6 MB, less than 21.65% of C++ online submissions for Median of Two Sorted Arrays.
+// 02/23/2020
+// MM/DD/YYYY
+// Suprisingly, shell sort has the fastest runtime for this method out of other sorting algorithms, such as
+// quicksort, merge sort, and merging (from merge sort)
+
+std::vector<int> shell_sort(std::vector<int> &array) {
+    int gap = array.size()/2;
+    while (gap >= 1) {
+        for (int i = gap; i < array.size(); i++) { //iterate through array, starting from gap
+            int comparator = array[i]; //make comparisons with this
+            int output; //for accessing x outside the array
+            int index; //for negative indexes
+
+            for (int x = i; x > gap-2; x -= gap) { //iterate throguh array with gap as the step
+                output = x; //to access x outside the loop
+                if (x-gap < 0) { //in case of negative index
+                    index = array.size()-x-gap;
+                } else {
+                    index = x-gap;
+                }
+
+                if (array[index] <= comparator) { //break when correct spot is found
+					break;
+				} else { //otherwise, move elements forward to make space
+					array[x] = array[index];
+				}
+            }
+            array[output] = comparator; //insert comparator in the correct spot
+        }
+        gap /= 2; //increment the gap
+    }
+    return array;
+}
+
+std::vector<int> combine(std::vector<int> &array1, std::vector<int> &array2) {
+    std::vector<int> array = array1;
+    array.insert(array.end(), array2.begin(), array2.end());
+    return array;
+}
+
+class Solution {
+public:
+    double findMedianSortedArrays(std::vector<int>& nums1, std::vector<int>& nums2) {
+        std::vector<int> array = combine(nums1, nums2);
+        std::vector<int> sorted = shell_sort(array);
+        if (array.size() % 2 == 1) {
+            return array[double(array.size())/2];
+        } else {
+            return double(array[float(array.size())/2] + array[float(array.size())/2-1]) / 2;
+        }
+    }
+};