神秘常量

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原文参考http://www.cnblogs.com/mq0036/p/6647383.html 和matrix67的博文

用c++写了下，获得了其中一个“神秘常量” hex: 0x04653adf bin:00000100 01100101 00111010 11011111 注意神秘常量的前4位一定要是0

#include <iostream>#include <string>#include <list>#include <algorithm>#include <cstdlib>using namespace std;typedef unsigned int uint_32;class DeBruijn{public:uint_32 newNum;string newStr;uint_32 newArr[32];list<string> l;DeBruijn(){}~DeBruijn() {}/*uint_32 exist = 0x077CB531;uint_32 exist_arr[32] = { 0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9 };uint_32 getBitPos_exist(int v) {return exist_arr[((uint_32)((v & -v) * exist)) >> 27];}*/uint_32 getBitPos_new(int v) {return newArr[((uint_32)((v & -v) * newNum)) >> 27];}void getnew(string str) {string tmp_str = str.substr(1, 4);string tmp_str0 = tmp_str + "0";string tmp_str1 = tmp_str + "1";if (l.size() == 32) {cout << "ok" << endl;getNum_new();getArr_new();return;}if (find(l.begin(), l.end(), tmp_str0) == l.end() && l.size() != 32) {l.push_back(tmp_str0);getnew(tmp_str0);if (l.size() == 32)return;l.pop_back();}if (find(l.begin(), l.end(), tmp_str1) == l.end() && l.size() != 32) {l.push_back(tmp_str1);getnew(tmp_str1);if (l.size() == 32)return;l.pop_back();}}void getNum_new() {string res_str = l.front();uint_32 res_uint;list<string>::iterator index = l.begin();index++;for (int n = 1; n <= 27; n++) {res_str += (*index).substr(4, 1);index++;}newStr = res_str;res_uint = strtol(res_str.c_str(), NULL, 2);newNum = res_uint;}void getArr_new() {for (int i = 0; i < 32; i++) {int index = ((uint_32)(newNum << i)) >> 27;newArr[index] = i;}}};int main(){DeBruijn db = DeBruijn();//uint_32 res = db.getBitPos(123456);//cout << res << endl;db.l.push_back("00000");db.getnew("00000");cout << "bin: " << db.newStr << endl;cout << hex << "hex： " << db.newNum << endl;//for (list<string>::iterator i = db.l.begin(); i != db.l.end(); i++)//cout <<(*i) << endl;uint_32 res = db.getBitPos_new(123456);cout << "the zero number of suffix: " << res << endl;return 0;}

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