update merge-sort to reflect API update

sorting.cpp

@@ -3,49 +3,70 @@
 #include "sorting.h"
 using namespace std;
 vector<int> merge(vector<int> arr1, vector<int> arr2){
-	int n1=arr1.size(), n2=arr2.size(),count1=0,count2=0;
-	vector<int> mergedArray(n1+n2);
-	for(int i=0;i<n1+n2;i++){
-		if(count1>=n1){
-			mergedArray[i]=arr2[count2];
-			count2++;
-		}
-		else if(count2>=n2){
-			mergedArray[i]=arr1[count1];
-			count1++;
-		}
-		else{
-			if(arr1[count1]<=arr2[count2]){
-				mergedArray[i]=arr1[count1];
-				count1++;
-			}
-			else{
-				mergedArray[i]=arr2[count2];
-				count2++;
-			}
-		}
-	}
-	return mergedArray;
+        int n1=arr1.size(), n2=arr2.size(),count1=0,count2=0;
+        vector<int> mergedArray(n1+n2);
+        for(int i=0;i<n1+n2;i++){
+                if(count1>=n1){
+                        mergedArray[i]=arr2[count2];
+                        count2++;
+                }
+                else if(count2>=n2){
+                        mergedArray[i]=arr1[count1];
+                        count1++;
+                }
+                else{
+                        if(arr1[count1]<=arr2[count2]){
+                                mergedArray[i]=arr1[count1];
+                                count1++;
+                        }
+                        else{
+                                mergedArray[i]=arr2[count2];
+                                count2++;
+                        }
+                }
+        }
+        return mergedArray;
 }
-vector<int> sort_custom(vector<int> arr){
-	int n=arr.size();
-	if(n==1){
-		return arr;
-	}
-	else
-	{
-		int n1=n/2;
-		int n2=n-n1;
-		vector<int> arr1(n1),arr2(n2);
-		for(int i=0;i<n;i++){
-			if(i<n1)
-				arr1[i]=arr[i];
-			else if(i<n1+n2)
-				arr2[i - n1]=arr[i];
-		}
-		vector<int> ans1=sort_custom(arr1);
-		vector<int> ans2=sort_custom(arr2);
-		vector<int> ans=merge(ans1,ans2);
-		return ans;
-	}
+vector<int> mergeSort(vector<int> arr){
+        int n=arr.size();
+        if(n==1){
+                return arr;
+        }
+        else
+        {
+                int n1=n/2;
+                int n2=n-n1;
+                vector<int> arr1(n1),arr2(n2);
+                for(int i=0;i<n;i++){
+                        if(i<n1)
+                                arr1[i]=arr[i];
+                        else if(i<n1+n2) 
+                                arr2[i - n1]=arr[i];
+                }
+                vector<int> ans1=mergeSort(arr1);
+                vector<int> ans2=mergeSort(arr2);
+                vector<int> ans=merge(ans1,ans2);
+                return ans;
+        }
+}
+
+vector<int> sort_custom(vector<int> arr,int startidx,int endidx){
+        int n=arr.size();
+        vector<int> subArr(endidx-startidx+1);
+        for(int i=startidx;i<=endidx;i++)
+                subArr[i-startidx]=arr[i];
+        vector<int> ans(n);
+        subArr=mergeSort(subArr);
+        for(int i=0;i<n;i++)
+        {
+                if(i>=startidx && i<=endidx)
+                {
+                        ans[i]=subArr[i - startidx];
+                }
+                else
+                {
+                        ans[i]=arr[i];
+                }
+        }
+        return ans;
 }