這份2012年微軟暑期實習生招聘筆試題來自網上資料，我將其抄出來便於閱讀和保存。秋季找工作的計算機畢業生建議先自己做一遍，然后再尋找答案。
末尾也附有我自己的一份答案，但不保證是正確的。如果您有不一致的答案，歡迎留言交流。
2012 Microsoft Intern Hiring Written Test
1. Suppose that a Selection Sort of 80 items has completed 32 iterations of the main loop. How many items are now guaranteed to be in their final spot (never to be moved again)?
(A) 16 (B) 31 (C) 32 (D) 39 (E) 40
2. Which Synchronization mechanism(s) is/are used to avoid race conditions among processes/threads in operating systems?
(A) Mutex (B) Mailbox (C) Semaphore (D) Local procedure call
3. There is a sequence of n numbers 1, 2, 3,.., n and a stack which can keep m numbers at most. Push the n numbers into the stack following the sequence and pop out randomly. Suppose n is 2 and m is 3, the output sequence may be 1, 2 or 2, 1, so we get 2 different sequences. Suppose n is 7 and m is 5, please choose the output sequences of the stack:
(A) 1, 2, 3, 4, 5, 6, 7
(B) 7, 6, 5, 4, 3, 2, 1
(C) 5, 6, 4, 3, 7, 2, 1
(D) 1, 7, 6, 5, 4, 3, 2
(E) 3, 2, 1, 7, 5, 6, 4
4. What is the result of binary number 01011001 after multiplying by 0111001 and adding 1101110?
(A) 0001 0100 0011 1111
(B) 0101 0111 0111 0011
(C) 0011 0100 0011 0101
5. What is output if you compile and execute the following code?
void main()
{
int i = 11;
int const *p = &i;
p++;
printf("%d", *p);
}
(A) 11 (B) 12 (C) Garbage value (D) Compile error (E) None of above
6. Which of following C++ code is correct?
(A) int f()
{
int *a = new int(3);
return *a;
}
(B) int *f()
{
int a[3] = {1, 2, 3};
return a;
}
(C) vector<int> f()
{
vector<int> v(3);
return v;
}
(D) void f(int *ret)
{
int a[3] = {1, 2, 3};
ret = a;
return;
}
7. Given that the 180-degree rotated image of a 5-digit number is another 5-digit number and the difference between the numbers is 78633, what is the original 5-digit number?
(A) 60918 (B) 91086 (C) 18609 (D) 10968 (E) 86901
8. Which of the following statements are true?
(A) We can create a binary tree from given inorder and preorder traversal sequences.
(B) We can create a binary tree from given preorder and postorder traversal sequences.
(C) For an almost sorted array, insertion sort can be more effective than Quicksort.
(D) Suppose T(n) is the runtime of resolving a problem with n elements, T(n) = Θ(1) if n = 1; T(n) = 2T(n/2) + Θ(n) if > 1; so T(n) is Θ(n log n).
(E) None of the above.
9. Which of the following statements are true?
(A) Insertion sort and bubble sort are not effcient for large data sets.
(B) Quick sort makes O(n^2) comparisons in the worst case.
(C) There is an array: 7, 6, 5, 4, 3, 2, 1. If using selection sort (ascending), the number of swap operation is 6.
(D) Heap sort uses two heap operations: insertion and root deletion.
(E) None of above.
10. Assume both x and y are integers, which one of the followings returns the minimum of the two integers?
(A) y ^ ((x ^ y) & ~(x < y))
(B) y ^(x ^ y)
(C) x ^ (x ^ y)
(D) (x ^ y) ^ (y ^ x)
(E) None of the above
11. The Orchid Pavilion (蘭亭集序) is well known as the top of "行書" in history of Chinese literature. The most fascinating sentence "Well I know it is a lie to say that life and death is the same thing, and that longevity and early death make no difference! Alas!" ("周知一死生為虛誕， 齊彭殤為妄作。") By counting the characters of the whole content (in Chinese version), the result should be 391 (including punctuation). For these characters written to a text file, please select the possible file size without any data corrupt.
(A) 782 bytes in UTF-16 encoding
(B) 784 bytes in UTF-16 encoding
(C) 1173 bytes in UTF-8 encoding
(D) 1176 bytes in UTF-8 encoding
(E) None of the above
12. Fill the blanks inside class definition
class Test
{
public:
____ int a;
____ int b;
public:
Test::Test(int _a, int _b) : a(_a) {b = _b;}
};
int Test::b;
int _tmain(int argc, __TCHAR *argv[])
{
Test t1(0, 0), t2(1, 1);
t1.b = 10;
t2.b = 20;
printf("%u %u %u %u", t1.a, t1.b, t2.a, t2.b);
}
Running result: 0 20 1 20
(A) static/const
(B) const/static
(C) --/static
(D) const static/static
(E) None of the above
13. A 3-order B-tree has 2047 key words, what is the maximum height of the tree?
(A) 11 (B) 12 (C) 13 (D) 14
14. In C++, which of the following keyword(s) can be used on both a variable and a function?
(A) static (B) virtual (C) extern (D) inline (E) const
15. What is the result of the following program?
char* f(char *str, char ch)
{
char *it1 = str;
char *it2 = str;
while (*it2 != '\0') {
while (*it2 == ch) {
it2++;
}
*it1++ = *it2++;
}
return str;
}
void main(int argc, char *argv[])
{
char *a = new char[10];
strcpy(a, "abcdcccd");
cout << f(a, 'c');
}
(A) abdcccd (B) abdd (C) abcc (D) abddcccd (E) Access Violation
16. Consider the following definition of a recursive function, power, that will perform exponentiation.
int power(int b, int e)
{
if (e == 0) return 1;
if (e %2 == 0) return power (b * b, e / 2);
return b * power(b * b, e / 2);
}
Asymptotically (漸進地) in terms of the exponent e, the number of calls to power that occur as a result of the call power(b, e) is
(A) logarithmic (B) linear (C) quadratic (D) exponential
17. Assume a full deck of cards has 52 cards, 2 black suits (spade and club) and 2 red suits (diamond and heart).
If you are given a full deck, and a half deck (with 1 red suit and 1 black suit), what's the possibility for each one getting 2 red cards if taking 2 cards?
(A) 1/2, 1/2 (B) 25/102, 12/50 (C) 50/51, 24/25 (D) 25/51, 12/25 (E) 25/51, 1/2
18. There is a stack and a sequence of n numbers (i.e., 1, 2, 3, ..., n). Push the n numbers into the stack following the sequence and pop out randomly. How many different sequences of the number we may get? Suppose n is 2, the output sequence may be 1, 2 or 2, 1, so we get 2 different sequences.
(A) C_2n^n
(B) C_2n^n - C_2n^(n + 1)
(C) ((2n)!) / (n + 1)n!n!
(D) n!
(E) None of the above
19. Longest Increasing Subsequence (LIS) means a sequence containing some elements in another sequence by the same order, and the values of elements keeps increasing.
For example, LIS of {2, 1, 4, 2, 3, 7, 4, 6} is {1, 2, 3, 4, 6}, and its LIS length is 5.
Considering an array with N elements, what is the lowest time and space complexity to get the length of LIS?
(A) Time: N^2, Space: N^2
(B) Time: N^2, Space: N
(C) Time: NlogN, Space: N
(D) Time: N, Space: N
(E) Time: N, Space: C
20. What is the output of the following piece of C++ code?
#include <iostream>
using namespace std;
struct Item
{
char c;
Item *next;
};
Item *Routine1(Item *x)
{
Item *prev = NULL, *curr = x;
while (curr) {
Item *next = curr->next;
curr->next = prev;
prev = curr;
curr = next;
}
return prev;
}
void Routine2(Item *x)
{
Item *curr = x;
while (curr) {
cout << curr->c << " ";
curr = curr->next;
}
}
void _tmain(void)
{
Item *x,
d = {'d', NULL},
c = {'c', &d},
b = {'b', &c},
a = {'a', &b};
x = Routine1(&a);
Routine2(x);
}
(A) cbad (B) badc (C) dbca (D) abcd (E) dcba
答案在這里（設成了白色，反選可見）：
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1. C 2. AC 3. AC 4. A 5. C 6. None 7. D 8. ACD 9. ABD 10. E
11. C 12. C 13. A 14. ACE 15. B 16. A 17. B 18. BC 19. B 20. E
注：第11題是我實驗得到的答案，您要是沒答對，完全不用捉急，這個估計沒幾個能猜對。
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