Merge Sort | Code and Explanation | C++ Course – 19.1 | Bảng Tin về chủ đề merge sort c++ |

Thanks

this algorithm is completely wrong you should not teach wrong algorithms CHECK IT FOR {5,4,6,3,7,2,8,1} this will not give shorted array. Your algorithm works only for decreasing ordered array like{6,5,4,3,2,1} I also copy-paste your algorithm but id does not work

} #include<bits/stdc++.h>

using namespace std;

void merge(int arr[],int l,int mid,int r){

int n1=mid-l+1;

int n2=r-mid;

int a[n1];

int b[n2];

for(int i=0;i<n1;i++){

a[i]=arr[l+i];

}

for(int i=0;i<n2;i++){

b[i]=arr[mid+1+i];

}

int i=0;

int j=0;

int k=l;

while(i<n1 && j<n2){

if(a[i]<b[i]){

arr[k]=a[i];

k++;

i++;

}

else{

arr[k]=b[j];

k++;

j++;

}

}

while(i<n1){

arr[k]=a[i];

k++;i++;

}

while(j<n2){

arr[k]=b[j];

k++;j++;

}

}

void mergesort(int arr[],int l,int r){

if(l<r){

int mid=(l+r)/2;

mergesort(arr,l,mid);

mergesort(arr,mid+1,r);

merge(arr,l,mid,r);

}

}

int main(){

int arr[]={5, 4 ,6 ,3, 7 ,2, 8 ,1};

mergesort(arr,0,7);

for(int i=0;i<8;i++){

cout<<arr[i]<<" ";

}

cout<<endl;

return 0;

}

what is the values in n1 and n2

87k views and only 2.5k likes shows that this series is not for beginners but for who already know the basics!!!!

I didn't understand the time complexity part

accha explanation tha bs thoda code dry run kr k batate tho zyada accha hota

A smaller function is below. merge function is reduced
void merge(int arr[], int l, int mid, int r)

{

int n1 = mid – l + 1;

int n2 = r – mid;

// different from video –> one extra element

int a[n1 + 1];

int b[n2 + 1];

//maximize the extra element

a[n1]=INT_MAX;

b[n2]=INT_MAX;

for (int i = 0; i < n1; i++)

{

a[i] = arr[l + i];

}

for (int i = 0; i < n2; i++)

{

b[i] = arr[mid + 1 + i];

}

int i = 0;

int j = 0;

int k = l;

// different from video –> using or ( || )

while (i < n1 || j < n2)

{

if (a[i] < b[j])

{

arr[k] = a[i];

k++;

i++;

}

else

{

arr[k] = b[j];

k++;

j++;

}

}

}

Sound problem..
Beech beech mae volume km hoo jaati hai

Thanks a lot for this video

14:00

Aman bhaiya ❤️❤️❤️❤️❤️❤️
I want to know the concept of
Int**arr =new*arr

this only works for reversed ex
try it guys