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  1.  
  2. #include<bits/stdc++.h>
  3. using namespace std;
  4.  
  5. void merge(int arr[],int l,int mid,int r){
  6.     int n1= mid-l+1;
  7.     int n2= r-mid;
  8.  
  9.     //temp arrays
  10.     int a[n1];
  11.     int b[n2];
  12.  
  13.     //array ke elements ko 2 temp arrays mein bhar rhe hai
  14.     for (int i = 0; i < n1; i++)
  15.     {
  16.         a[i]=arr[l+i];
  17.  
  18.     }
  19.     for (int i = 0; i < n2; i++)
  20.     {
  21.         b[i]=arr[mid+1+i];
  22.  
  23.     }
  24.  
  25.     //checing when putting the values backing in the k array
  26.     int i=0;
  27.     int j=0;
  28.     int k=l;
  29.     while(i<n1 && j<n2){
  30.         if(a[i]<b[j]){
  31.             arr[k]=a[i];
  32.             k++;
  33.             i++;
  34.         }
  35.         else{
  36.             arr[k]=b[j];
  37.             k++;
  38.             j++;
  39.         }
  40.     }
  41.  
  42.     // for the last one
  43.     while(i<n1){
  44.         arr[k]=a[i];
  45.         k++;
  46.         i++;
  47.     }
  48.     while(j<n2){
  49.         arr[k]=b[j];
  50.         k++;
  51.         j++;
  52.     }    
  53. }
  54.  
  55. void mergeSort(int arr[],int l,int r){
  56.     if(l<r){
  57.         int mid=(l+r)/2;
  58.         mergeSort(arr,l,mid);
  59.         mergeSort(arr,mid+1,r);
  60.         merge(arr,l,mid,r);
  61.     }
  62. }
  63.  
  64. int main(){
  65.     int arr[]={5,4,3,2,1};
  66.     mergeSort(arr,0,4);
  67.     for (int i = 0; i < 5; i++)
  68.     {
  69.         cout<<arr[i]<<" ";
  70.     }
  71.     cout<<endl;
  72.     return 0;
  73. }
Success #stdin #stdout 0.01s 5408KB
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https://ideone.com/r525sM
language:
C++ (gcc 8.3)
created:
1 year ago
visibility:
public

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