change implementation to merge-sort

sorting.cpp

-#include "sorting.h"
 #include<iostream>
-vector<int> sort_custom(vector<int> inp){
-	for (int i=0;i<inp.size();i++){
-		for (int j=1;j<inp.size();j++){
-			if (inp[j-1]>inp[j]){
-				int temp=inp[j];
-				inp[j]=inp[j-1];
-				inp[j-1]=temp;
-				}
+#include<vector>
+#include "sorting.h"
+
+using namespace std;
+
+vector<int> merge_fun(vector<int> array1, vector<int> array2){
+	int n1=array1.size(), n2=array2.size(),count1=0,count2=0;
+	vector<int> merged(n1+n2);
+	for(int i=0;i<n1+n2;i++){
+		if(count1>=n1){
+			merged[i]=array2[count2];
+			count2++;
+		}
+		else if(count2>=n2){
+			merged[i]=array1[count1];
+			count1++;
+		}
+		else{
+			if(array1[count1]<=array2[count2]){
+				merged[i]=array1[count1];
+				count1++;
+			}
+			else{
+				merged[i]=array2[count2];
+				count2++;
 			}
 		}
-	return inp;
+	}
+	return merged;
+}
+vector<int> sort_custom(vector<int> inp){
+	int n=inp.size();
+	if(n==1){
+		return inp;
+	}
+	else
+	{
+		int n1=n/2;
+		int n2=n-n1;
+		vector<int> array1(n1),array2(n2);
+		for(int i=0;i<n;i++){
+			if(i<n1)
+				array1[i]=inp[i];
+			else if(i<n1+n2)
+				array2[i - n1]=inp[i];
+		}
+		vector<int> out1=sort_custom(array1);
+		vector<int> out2=sort_custom(array2);
+		vector<int> ans=merge_fun(out1,out2);
+		return ans;
+	}
 }
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