cutting paper squares Hacker Rank Solution in C, Diwali Lights Hacker Rank Solution in C, modular arithmetic

https://www.hackerrank.com/challenges/p1-paper-cutting/problem

Explanation:
when we cut n x m paper into n horizontal pieces using n-1 cuts
each of these n horizontal pieces can be cut using m-1 cuts
so number of cuts= n-1+(n*(m-1))
when we simplify n-1+(n*(m-1))  we get n-1+n*m -n =n*m-1


Program:

long solve(long int n, long int m)
{

return (n-1)+(n *(m-1)); // we can simplify it as n-1+nm-n tht is nm-1
}

Diwali Lights

https://www.hackerrank.com/challenges/diwali-lights/problem

Explanation: each bulb can have 2 states "on" or "off"

if there are n bulbs then we can get 2 power n combinations.

Since we cannot count all bulbs off as pattern so answer is 2 power n-1

Function:

long lights(unsigned long long int n)
{

unsigned long long int i,ans=1;
for(i=1;i<=n;i++)
{
ans =(ans%100000*2)%100000;
}
return ans-1;
}

or complete program is below

#include<stdio.h>

int main()

{

    int t;

    scanf("%d",&t);

    while(t--)

    {

    unsigned long long int n,i,ans=1;

    scanf("%llu",&n);

    for(i=1;i<=n;i++)

        ans =(ans%100000*2)%100000;

    printf("%llu\n",ans-1);

    }

}

Link to modular arithmetic used in competitive programming is below

https://www.hackerearth.com/practice/math/number-theory/basic-number-theory-1/tutorial/ Day 2 operators

Problem:

https://www.hackerrank.com/challenges/30-operators/problem

Solution:

#include<stdio.h> #include <math.h> int main() { float mc,tipper,taxper,tip,tax,tc; scanf("%f%f%f",&mc,&tipper,&taxper); tip=(mc*tipper/100); tax=(mc*taxper/100); tc=round(mc+tip+tax); printf("%.0f",tc); }