[問題] 使用全域變數的權衡

看板C_and_CPP作者howardxu (好噁)時間12年前 (2013/03/25 08:39)推噓6(6推 0噓 28→)

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問題(Question)：在寫acm題目的時候，常常遇到好像用全域變數會比較容易處理的情況? 以101 The block problem來說，我的寫法是用一個二維的vector來當作方塊，一些動作則寫在function中。我的問題是，如果不用全域變數，function的參數就都要加上這個vector。但是大家又說盡量不要用全域變數，哪麼有什麼其它的寫法嗎? 謝謝程式碼(Code)：(請善用置底文網頁, 記得排版) #include <iostream> #include <string> #include <vector> #include <algorithm> #include <stack> using namespace std; void reset_desk(vector<vector<int> > &desk, int n) { desk.clear(); desk.resize(n); for (int i=0; i<n; i++) desk[i].push_back(i); } int find_block(const vector<vector<int> > &desk, const int block ) { for (int i = 0; i < desk.size(); ++i) { vector<int>::const_iterator it = find(desk[i].begin(), desk[i].end(), block); if (it != desk[i].end()) { return i; } } } void print_desk(const vector<vector<int> > &desk) { for (int i = 0; i < desk.size(); ++i) { cout << i << ":"; for (vector<int>::const_iterator it=desk[i].begin(); it != desk[i].end(); ++it) { cout <<" " << *it; } cout << endl; } } void clean_top(vector<vector<int> > &desk, const int block) { int temp; int pos = find_block(desk, block); while (desk[pos].back() != block) { temp = desk[pos].back(); desk[temp].push_back(temp); desk[pos].pop_back(); } } void move(vector<vector<int> > &desk, const int from_block, const int to_block) { stack<int> temp; int from = find_block(desk, from_block); while (desk[from].back() != from_block) { temp.push( desk[from].back() ); desk[from].pop_back(); } temp.push(desk[from].back()); desk[from].pop_back(); int to = find_block(desk, to_block); while( !temp.empty() ) { desk[to].push_back( temp.top() ); temp.pop(); } //print_desk(desk); //cout << endl; } void execute (vector<vector<int> > &desk, const string cmd1, const int a, const string cmd2, const int b) { //cout << cmd1 << " " << a << " " << cmd2 << " " << b << endl; if (cmd1 == "move") clean_top(desk, a); if (cmd2 == "onto") clean_top(desk, b); move (desk, a, b); } bool invalid_command(const vector<vector<int> > desk, const int a, const int b) { int pos_a, pos_b; pos_a = find_block( desk, a ); pos_b = find_block( desk, b ); return (a == b || pos_a == pos_b); } int main() { int n, a, b; int pos_a, pos_b; //position for a and b string cmd1, cmd2; vector< vector<int> > desk; //----------testing------------ freopen ("101.in", "r", stdin); freopen ("101.out", "w", stdout); while (cin >> n) { reset_desk(desk, n); while (1) { cin >> cmd1; if (cmd1 == "quit") break; cin >> a >> cmd2 >> b; if (invalid_command(desk, a, b)) continue; execute(desk, cmd1, a, cmd2, b); } print_desk(desk); } return 0; } 補充說明(Supplement)：我是用C++寫的~~ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 114.32.170.48 ※ 編輯: howardxu 來自: 114.32.170.48 (03/25 08:42)

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