[模拟]位运算实现四则运算

 1 const int mod = 1000;
 2 
 3 int bitpow(int x, int n) {
 4     int ans = 1;
 5     int t = x;
 6     while(n) {
 7         if(n & 1) {
 8             ans = (ans * t) % mod;
 9         }
10         t = t * t % mod;
11         n >>= 1;
12     }
13     return ans;
14 }
15 
16 int bitadd(int x, int y) {
17     int xr = x ^ y;
18     int nd = x & y;
19     while(nd) {
20         int xr1 = xr;
21         int nd1 = nd << 1;
22         xr = xr1 ^ nd1;
23         nd = xr1 & nd1;
24     }
25     return xr;
26 }
27 
28 int negtive(int x) {
29     return bitadd(~x, 1);
30 }
31 
32 int bitminus(int x, int y) {
33     return bitadd(x, negtive(y));
34 }
35 
36 int bitmulti(int x, int y) {
37     int ans = 0;
38     while(y) {
39         if(y & 1) {
40             ans = bitadd(ans, x);
41         }
42         x = (x << 1);
43         y = (y >> 1);
44     }
45     return ans;
46 }
47 
48 int bitdiv(int x, int y) {
49     int ans = 0;
50     for(int i = 31; i >= 0; i--) {
51         if((x>>i) >= y) {
52             ans += (1<<i);
53             x -=(y<<i);
54         }
55     }
56     return ans;
57 }

 

posted @ 2015-08-09 23:31  Kirai  阅读(202)  评论(0编辑  收藏  举报