《Cracking the Coding Interview》——第5章：位操作——题目1

2014-03-19 05:45

题目：给定两个数M和N，将N按照二进制位，覆盖到M的特定段位中去。

解法：位操作，请看代码。

代码：

 1 // 5.1 Insert one number into the certain bit segment of another number.

 2 #include <cstdio>

 3 using namespace std;

 4 

 5 void printBinary(unsigned num)

 6 {

 7     unsigned bit = 1 << 31;

 8     

 9     do {

10         putchar('0' + !!(num & bit));

11         bit >>= 1;

12     } while (bit);

13 }

14 

15 unsigned insertBits(unsigned n, unsigned m, int ll, int rr)

16 {

17     return (n >> (rr + 1) << (rr + 1)) + (m << ll) + (n - (n >> ll << ll));

18 }

19 

20 int main()

21 {

22     unsigned n, m;

23     unsigned res;

24     int low, high;

25     

26     while (scanf("%u%u", &n, &m) == 2) {

27         scanf("%d%d", &low, &high);

28         res = insertBits(n, m, low, high);

29         printBinary(n);

30         putchar('\n');

31         printBinary(m);

32         putchar('\n');

33         printBinary(res);

34         putchar('\n');

35     }

36     

37     return 0;

38 }