USACO Contact，难题，运算符重载，QuickSort，

我感觉是到目前为止最难的一题
参考消逝者的代码：http://www.nocow.cn/index.php/Code:USACO/contact/C%2B%2B
参考思路：http://www.nocow.cn/index.php/USACO/contact#.E7.AE.80.E6.98.93.E4.BD.86.E9.9D.9E.E5.B8.B8.E9.AB.98.E6.95.88.E7.9A.84.E6.96.B9.E6.B3.95

简易但非常高效的方法 消逝者

/* ID: wangxin12 PROG: contactLANG: C++ */ #include <iostream>#include <vector>#include <fstream>#include <string>#include <cstring>using namespace std;#define MAX 999999999int A, B, N;int frequency[12][4100];int transform, length;int const_num[13] = { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096 };class unit {public:int frequency, length, num;};vector<unit> unit_pool;string original_string;void create_unit(int length, int num) {unit * u = new unit();u->frequency = frequency[length - 1][num];u->length = length;u->num = num;unit_pool.push_back(*u);}bool operator>(unit u1, unit u2) {if( (u1.frequency < u2.frequency) ||(u1.frequency == u2.frequency && u1.length > u2.length) ||(u1.frequency == u2.frequency && u1.length == u2.length && u1.num > u2.num) )return true;elsereturn false;}template<typename T>int partition(vector<T> &f, int start, int end) {T key = f[start];int left = start + 1, right = end;while(true) {while(left < right && f[right] > key) right--;while(left < right && key > f[left]) left++;if(left == right) break;T tmp = f[left];f[left] = f[right];f[right] = tmp;}if(f[left] > key) return start;f[start] = f[left];f[left] = key;return left;}template<typename T> void quick_sort(vector<T> &f, int start, int end) {if(start >= end) return;int boundary = partition(f,  start, end);quick_sort(f, start, boundary - 1);quick_sort(f, boundary + 1, end);}string transform_to_binary(int num, int length) {string s1 = "", s2 = "";int t = num;char tmp;while(t != 0) {s1 += (t % 2 + '0');t /= 2;}for(int j = s1.length() - 1; j >= 0; j--)s2 += s1[j];s1 = "";for(int i = 1; i <= length - s2.length(); i++) s1 += '0';s1 = s1 + s2;return s1;}int main() {ifstream fin("contact.in");ofstream fout("contact.out");fin>>A>>B>>N;//original_string要一个char一个char的读入，否则读到换行符就停止了char ch;while(fin.get(ch)) {if(ch >= '0' && ch <= '1')original_string += ch;}//for(length = A; (length <= B) && (length <= original_string.size()); length++) {for(int start = 0; start <= original_string.length() - length; start++) {transform = 0;for(int j = start; j <= start + length - 1; j++) //for使transform记载字符串大小if(original_string[j] == '1')transform += const_num[start + length - j - 1];frequency[length - 1][transform]++;}}for(int i = A; i <= B; i++) {for(int j = 0; j < const_num[i]; j++) {if(frequency[i - 1][j] != 0)create_unit(i, j);}}quick_sort(unit_pool, 0, (int)unit_pool.size() - 1);int last_frequency = 99999999, sum = 0, count = 0;for(int k = 0; k < unit_pool.size(); k++) {if(unit_pool[k].frequency < last_frequency) {sum++;if(sum == N + 1) break;if(k != 0) fout<<endl;count = 1;fout<<unit_pool[k].frequency<<endl;fout<<transform_to_binary(unit_pool[k].num, unit_pool[k].length);last_frequency = unit_pool[k].frequency;} else {count++;if(count == 7) {fout<<endl;count = 1;} elsefout<<" ";fout<<transform_to_binary(unit_pool[k].num,unit_pool[k].length);}}fout<<endl;fin.close();fout.close();return 0;}