《Cracking the Coding Interview》——第17章：普通题——题目1

 1 // 17.1 Do a swapping in-place.
 2 #include <cstdio>
 3 using namespace std;
 4 
 5 void swap1(int &x, int &y)
 6 {
 7     if (x == y) {
 8         return;
 9     }
10 
11     // what if it is double?
12     x ^= y ^= x ^= y;
13 }
14 
15 void swap2(int &x, int &y)
16 {
17     if (x == y) {
18         return;
19     }
20 
21     // overflow?
22     x = x + y;
23     y = x - y;
24     x = x - y;
25 }
26 
27 void swap3(int &x, int &y)
28 {
29     if (x == y) {
30         return;
31     }
32     
33     x = x ^ y;
34     y = x ^ y;
35     x = x ^ y;
36 }
37 
38 int main()
39 {
40     int x, y;
41     
42     scanf("%d%d", &x, &y);
43     printf("x = %d, y = %d\n", x, y);
44     swap1(x, y);
45     printf("x = %d, y = %d\n", x, y);
46     swap2(x, y);
47     printf("x = %d, y = %d\n", x, y);
48     swap3(x, y);
49     printf("x = %d, y = %d\n", x, y);
50     
51     return 0;
52 }