New to C++ finding results of an if and else function [closed] - c++

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result = getResult( 2, 5)
  
int getResult(int m, int n)
{
int ans;
if (m < n)
  if (n <= 10)    
ans = m + n;
else
   ans = m * n;
else
ans = n / m;
return (ans);
}
I am stuck between 10 and 2,
does the second else apply because the second if is true? or do i still go with the first else?

For m = 2, n = 5, the first two if conditions are valid: m < n and n <= 10. Thus, ans = m + n = 7 and it's not modified later on, so we expect 7 as the answer.
This can be much easier deduced if you properly format your code (I did it for you in this case). Also, if you use {} in if/else, that's way easier and less error-prone.

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what is for (; e > 0; e >>= 1)? [closed]

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Can anyone explain to me what's happening in line number 4, and how to understand these types of loops in future.
I was solving this problem. I have used basic approaches like pow(2,n) and (1<<n), but it overflows. Then I got this solution, but I'm unable to understand that fourth line. I know how to use for() loops in C++, but I'm a bit confused because of starting, i.e. nothing is there i.e. for(; e > 0; e >>= 1).
long long modpow(long long b, int e)
{
long long ans = 1;
for (; e > 0; e >>= 1)
{
if (e & 1)
ans = (ans * b) % mod;
b = (b * b) % mod;
}
return ans;
}
The for loop has 3 components:
for (a; b; c) {
}
a runs at the start. The loop will break when b is no longer true, and after each iteration c is executed.

Dart program to group consecutive number from given numbers in a list<list> [closed]

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Suppose you are given a list of numbers like this
[11,2,7,6,17,13,8,9,3,5,12]
The result will be a group of numbers list containing sub-list i.e.,
[[2,3],[5,6,7,8,9],[11,12,13],[17]]
Here is my solution to the problem:
List<List<int>> consecutive_groups(List<int> a) {
a.sort();
List<List<int>> result = [];
List<int> temp = [];
temp.add(a[0]);
for (int i = 0; i < a.length - 1; i++) {
if (a[i + 1] == a[i] + 1) {
temp.add(a[i + 1]);
} else {
result.add(temp);
temp = [];
temp.add(a[i + 1]);
}
}
result.add(temp);
return result;
}

How to implement this exercise (dynamic array)? [closed]

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I'm having like an assesment exercise.
So given a Number, for example 12345, I must find out the sum sequence of the digits of the given number (1 + 2 +3 + 4 +5) and then add to it the result (15), and repeat this till the sum sequence of the last number is a digit (in this case is 6).
Example : 12345 + 15 + 6 = 12366;
666 + 24 + 6 = 696;
I've been thinkig to store the digits in an array, but then I realized the array's size is static. Now I'm thinking to make a linked list, but I'm not really sure. Does it involve linked lists?
Just guide me to the right path. What should I use?
There's no magic needed here. Just do the obvious computation on integers:
int reduce(int n)
{
int result = 0;
while (n != 0) { result += n % 10; n /= 10; }
return result;
}
int your_problem(int n)
{
int result = n;
while (n >= 10) { n = reduce(n); result += n; }
return result;
}

A fibonacci like Algorithm [closed]

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For f(n) = f(n – 1) + f(n – 2^10), when 0 <= n < 2^10, f(n)=1 ,
write a function to compute f(n).(not using recursive method)
int compute_f(int n)
{
int result = 0;
...
return result
}
wondering is there any efficient way to do?
You can follow the same idea of fibonacci and do Dynamic Programming.
Pseudo code:
if n < 0:
//throw some exception
arr = new int[max(1024,n+1)]
for i = 0 to 1024:
arr[i] = 1
for i = 1024 to n+1:
arr[i] = arr[i-1] + arr[i-1024]
return arr[n]
Converting it to actual code is left for you.
Bonus: You can do it with O(1) extra space by holding an array of size 1024 and manipulating it and remembering your current place (use modolus operator) without changing the time complexity.
Here is my version, similar to the recursive version of Fibonacci.
int compute_f(int n)
{
if( n < 0)
return -1; //Error
if(n <= 1024)
return 1;
return (compute_f(n-1) + compute_f(n-1024));
}

Stumped on solving a recurrence equation [closed]

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Here is the equation I'm working with (it's from a past exam question that I got wrong):
void foo(float[] array, int start, int end){
if((end-start) <= 1) return;
int x = (end-start) / 5;
int y = 2*x;
int z = 4*x;
foo(array,start,start+y);
for(index = y; index <z; index++){
array[index]++;
}
foo(array,start+z,end);
}
How would I go about coming up with a recurrence equation for this?
I'm not sure of the notation I should use since the function #recurrences is depending on the value of end-start...
T(1) = 1
T(N) = ____ + ____ + _____
for notation simplicity, lets call N = end-start
then:
foo(array,start,start+y); // T(2/5 * N)
for(index = y; index <z; index++) // 2/5 * N
foo(array,start+z,end); // T(N/5)
T(N) = T(2/5 * N) + 2/5 * N + T(N/5)
is that close enough?