Multiple choice
2-1
Which of the following functions is O(N)? (4 points)
A. 2NlogN
B. logN 2
C. N (lie) 2
D. N 2 /2
2-2
Given an N×N×N three-dimensional array A, the time complexity of finding the smallest element without changing the array is: (4 points)
A. O (N 2 )
B. O (nlogn)
C. O (N 3 logN)
D. O(N3)
2-4
The time complexity of the following code segment is (). (4 points)
x=0;
for( i=1; i<n; i++ )
for ( j=1; j<=n-i; j++ )
x++;
A. O(n)
B. O(n2)
C. O(n3)
D. O(2n)
2-5
following code
if ( A > B ) {
for ( i=0; i<N*N/100; i++ )
for ( j=N*N; j>i; j-- )
A += B;
}
else {
for ( i=0; i<N*2; i++ )
for ( j=N*3; j>i; j-- )
A += B;
}
The time complexity of is: (4 points)
A. O(N3)
B. O(N4)
C. O(N5)
D. O(N6)
2-6
following code
for(i=0; i<n; i++)
for(j=i; j>0; j/=2)
printf(“%d\n”, j);
The time complexity of is: (4 points)
A. O(N×i)
B. O(N)
C. O(N2)
D. O (NlogN)
The inner loop is divided by 2 each time, only log2 is the bottom, N times;
Programming questions
7-1 Find the maximum value and its subscript (80 points)
This question requires writing a program to find the maximum value of a given n number and its corresponding minimum subscript (subscript starts from 0).
Input format:
Input a positive integer n (1<n≤10) in the first line. Enter n integers on the second line, separated by spaces.
Output format:
output the maximum value and the minimum subscript of the maximum value in one line, separated by a space.
Input sample:
6
2 8 10 1 9 10
Sample output:
10 2
#include<iostream>
using namespace std;
int main()
{
int n;
cin >> n;
int A[n];
for(int i=0; i<n; i++){
cin >> A[i];
}
int max=A[0];
int max_key = 0;
for (int j=1; j<n; j++){
if(A[j] > max){
max = A[j];
max_key = j;
}
}
cout << max << " " << max_key;
}