C++笔记:二进制枚举子集的技巧
关于二进制枚举子集,读者可见https://www.jisuanke.com/course/8387/438021,这里就直接讲二进制枚举子集技巧。
一:多数二进制枚举子集题代码框架:
#include <iostream>
using namespace std;
int main() {
int n, x, ans = 0, a[30];
cin >> n >> x;
for (int i = 0; i < n; i++) {
cin >> a[i];
}
// 在这里写代码
for (int i=0;i<(1<<n);i++){
······
for (int j=0;j<n;j++){
if (i&(1<<j)){
······
}
}
······
}
//······
return 0;
}
二:二进制枚举子集时位运算的各种技巧:
位运算见https://blog.csdn.net/Keven_11/article/details/107715542
- A ^ A=0
- A ^ B ^ A=B
- 判断第i位是否是1:(x >> i)& 1
- 将第i位变为1:x | ( 1 << i )
- 将第i位取反:x ^ ( 1 << i)
- i是否是j的子集:x ^ (1<<i)
- i和j是否交为空:i & j == 0
- j中i的补集:j ^ i
- 按位思考:将二进制每一位做差,求最大则为1,最小则为0.
三:更多:
例题可见:https://blog.csdn.net/qq_42882717/article/details/100765224
与
https://blog.csdn.net/yiqzq/article/details/80243846?utm_medium=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param
,更多可见
https://blog.csdn.net/acvay/article/details/41285559?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param
与
https://blog.csdn.net/qq_41668093/article/details/82831903?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.channel_param