Question

For each implementation, answer the following question: Suppose I run this with a particular value of n, and it takes 10 seconds. Suppose I run it again, but I double the value of n. How long should I expect it to run?

Implementation 1
void Q4(vector <int> &v, int n) {
    int i;
    v.clear();
    for (i = 0; i < n; i++) v.push_back(i);
    for (i = 0; i < n; i++) v.push_back(i);
    for (i = 0; i < n; i++) v.push_back(i);
    for (i = 0; i < n; i++) v.push_back(i);
}

Implementation 2
void Q4(vector <int> &v, int n) {
    int i;
    v.clear();
    for (i = 0; i < n; i++) v.push_back(i);
  
Implementation 3
int Q4(int n) {
    if(n == 0) return 1;
    return 1 + Q4(n-1);
}

Implementation 4
int Q4(int n) {
    if(n == 0) return 1;
    return Q4(n-1) + Q4(n-1);
  
Implementation 5
void Q4(vector <int> &v, int n) {
    int i, j;
    v.clear();
    for (i = 0; i < n; i++) {
        for (j = 0; j < i; j++) v.push_back(i);
    }
    for (i = 0; i < n; i++) {
        for (j = 1; j < n; j *= 2) v.push_back(i+j);
    }
}

Choose your answers from the following multiple choice: Possible Answers: 1.) 20 seconds 2.) 10 seconds 3.) >60 seconds 4.) 44 seconds 5.) 40 seconds

Answer 1

1)  1.) 20 seconds
2)  1.) 20 seconds
3)  1.) 20 seconds
4)  3.) >60 seconds
5)  5.) 40 seconds