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## Discussion of Problem 1068. Sum

where is wrong !! already it is working in codeblocks
Posted by EIASER ARAFAT 6 Nov 2017 16:02
#include<stdio.h>

int main(){
int n,sum=0,i;
scanf("%d",&n);-

if(n>0){
sum=(n*(n+1))/2;
}
else if(n<0){
sum=(n*(-1*n+1))/2;
}
printf("%d",sum);

}
Re: where is wrong !! already it is working in codeblocks
Posted by Mahilewets Nikita 6 Nov 2017 19:46
Maybe for N < 0 the formula is
SUM = ((2-N)*(N+1))/2

Edited by author 06.11.2017 19:47
Re: where is wrong !! already it is working in codeblocks
Posted by Mahilewets Nikita 6 Nov 2017 19:55
The first term is N
The last term is 1
So the average is (1+N)/2

There are (-N) terms below zero
And there are two more terms
They are 0 and one
So there are (2-N) total terms

So the sum is average by total number of terms
Re: where is wrong !! already it is working in codeblocks
Posted by ToadMonster 7 Nov 2017 01:19
Case "N == 0" isn't processed
Re: where is wrong !! already it is working in codeblocks
Posted by jim 22 Feb 2018 07:10