UVa Problem 10077 The Stern-Brocot Number System （Stern-Brocot 代數系統）

// The Stern-Brocot Number System （Stern-Brocot 代數系統）// PC/UVa IDs: 110507/10077, Popularity: C, Success rate: high Level: 1// Verdict: Accepted// Submission Date: 2011-05-29// UVa Run Time: 0.016s//// 著作權（C）2011，邱秋。metaphysis # yeah dot net//// 直接根據題意，定義3個分數，根據要求的分數與中間分數比較大小決定向左還是向右。#include <iostream>using namespace std;struct fraction{long long unsigned numerator;long long unsigned denominator;};int main(int ac, char *av[]){long long unsigned up, down;fraction left, right, middle;while (cin >> up >> down, (up - down)){left.numerator = 0;left.denominator = 1;right.numerator = 1;right.denominator = 0;middle.numerator = 1;middle.denominator = 1;while (1){if (up * middle.denominator == down * middle.numerator)break;if (up * middle.denominator > down * middle.numerator){cout << "R";left.numerator =  middle.numerator;left.denominator = middle.denominator;middle.numerator = (left.numerator + right.numerator);middle.denominator = (left.denominator + right.denominator);}else{cout << "L";right.numerator =  middle.numerator;right.denominator = middle.denominator;middle.numerator = (left.numerator + right.numerator);middle.denominator = (left.denominator + right.denominator);}}cout << endl;}return 0;}