L-02 || ✅ Difference Array or Range Update Query || Algorithms

In this video we are going to discuss very interesting Algorithm - "Difference Array or Range Update Query" Which is very Useful in various problems and in Algorithms also.

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Competitive programming or CP is a buzzword when a guy is a freshie in computer science branch and most of the guys don't have proper guidance that is needed. So in this series of video lectures I will be guiding you through various problems, myths, future scopes and a lot more related exclusively to competitive programming.

[shuvbhowmickbestin]

very explanatory video! thanks for clearing my concepts

[utkarshsharma]

Code in JAVA:
public static void main(String[] args) {

int arr[]={5, 3, 1, 67, 3, 2};
int dif[]=new int[arr.length + 1];

int n = arr.length;
for (int i = 0; i < n; i++) {
if(i == 0)dif[i] = arr[i];
else dif[i] = arr[i] - arr[i-1];
}

int l = 2;
int r = 5;
int val = -10;

dif[l] += val;
dif[r+1] = dif[r+1] - val;

long tot = 0;
for (int i = 0; i < n; i++) {
tot += dif[i];
System.out.print(tot + " ");
}

System.out.println();

}
Thanks bhai for the amazing explanation

[AniketKumar-phkv]

U r the one who really helping 1 and 2yr student.... Bez I know how it's feels if u don't know about single word of compitative programing... It's bad.... So guys try to start compitative programing as soon as possible.. Its help u out... This channel is great...

[AJAYSINGH-ygre]

// diference array || Range update Query

#include <bits/stdc++.h>

using namespace std;

int main()
{
int n;
cout<<"enter the size of array"<<endl;
cin >> n;
int arr[n];
cout<<"enter the elements of array"<<endl;
for (int i = 0; i < n; i++)
{
cin >> arr[i];
}
int d[n+1];
for (int i = 0; i <= n; i++){
if (i == 0){
d[i] = arr[i];
}
else{
d[i] = arr[i]-arr[i-1];
}
}
// we have created a difference array
int l;
int r;
cout<<"enter the range you want to perform operation"<<endl;
cin>>l>>r;

int value;
cout<<"enter the value"<<endl;
cin>> value;

d[l] = d[l]+value;
d[r+1] = d[r+1]-value;

//now query is updated
// find the prefix sum array of difference array
cout<<"The updated array"<<endl;
for(int i = 0; i < n; i++) {
if(i==0){
arr[i] = d[i];
cout<<arr[i]<<" ";
}
else{
arr[i] = d[i]+d[i-1];
d[i] = d[i]+d[i-1];
cout<<arr[i]<<" ";
}
}
cout<<endl;
}

[randomdude]

Thanks Bhaiya, this approach helped me. Such a good but underrated channel.

[mohd.vaseem]

sir why you stopped delivering vedios in this playlist, are these 2 vedios enough or is this incomplete
please reply

[AZZ]

I'm searching for comepetative programing channel from last 15 days and I found this channel today. ...hopefully i will finish all in 1 week....great work bhaiya....keep it up...and bring more in algorithm series...

[avinash]

Thank You soo much sir...It's a great help...Your videos motivates me to do a lot of code with interest

[himanimehta]

sir kindly update with some more algorithms...please sir

[BhagyaRana]

Excellent Video and Explanation!Must watch for Beginners in CP!👌

[srajikagupta]

It's so nice to see such efforts you put on your videos .

[wasit-shafi]

thank bro...ur videos really helped me

[AmanGupta-tnhz]

need more videos like this, greatwork bro

[okkk]

Hello sir, i didn't understand that when we run first for loop for i<6 then how can we access arr[5], because it doesn't exist? Can anyone answer?

[siddeshas]

What about the next video on algorithm...??
It's 11 month gap....sit plz proceed it
....we are waiting...👍👍

[sharanvaitheeswaran]

hello sir, n times O(1) will give O(n) sir...not O(1)

[AZZ]

I hope samjh nhi aaya hoga...😂😂 nice bhaiya....apko barosa hai hmpe .

[rajamurishiva]

To update Array also we require O(n) time

[pradeepdotiyal]

Sir your video are amazing sir really.it motivated me as well


Keep on posting such videos so that we can apply the concepts on codchef

[_shubhamsaurav]

Great content .
You make everything so easy to understand.
Please continue this series..👍👍