Why is the time complexity O(n2) and not O(n)

#1

Predict the time complexity of the following recursive function, given the vector is of size N and the initial call is calSum(v, 0).

int sum = 0;

void calcSum(vector v, int i)

{

if(i == v.size())
    return;
sum += v[i];
calcSum(v, i+1);

}

#2

hi @pradyumn25jain since the vector is being passed by value, it will be copied to a new vector in each call. Copying the vector will take O(n) time, doing so n times will make the overall time complexity of the program as O(n*n)

#3

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