ZOJ-1192

来源：互联网发布：php http上传文件编辑：程序博客网时间：2024/06/07 06:38

又是一道题搞一晚上，我去啊，优化了N次，开始理解为简单BFS，搞完发现用judge测试数据有几组答案不对，DEBUG了半天，发现保留已经搜索过的状态的逻辑不对，改了改答案全对了，以为万事大吉，一提交MLE了。。你妹的string存的太多了，发现可以用int来优化，因为每位只有两种状态，优化后觉得这次总过了吧，一提交还是MLE，我擦了，只能再想还有没有能优化的地方，发现存已搜索状态可以不用set，用个bool数组可解决，数据大小最大为2^20，再次优化后提交后总算过了。。这次再不过我也没办法了。。真是蛋疼无比，发现所有提交中我用的内存应该的最小的，聊以自慰了。。

#include<cstdio>#include<iostream>#include<queue>#include<string>#include<vector>#include<cstring>using namespace std;namespace{struct Patch{int time;string from, to;};struct cmp{bool operator()(const pair<int, int> &p1, const pair<int, int> &p2){return p1.first > p2.first;}};bool match(const int &src, const string &pattern){int num = src;for (int i = pattern.size() - 1; i >= 0; i--){if (pattern[i] != '0'){char ch = num & 1 ? '+' : '-';if (ch != pattern[i])return false;}num >>= 1;}return true;}int patch(const int &src, const string &pattern){int res = 0;for (size_t i = 0; i < pattern.size(); i++){res <<= 1;if (pattern[i] == '0')res |= (src >> (pattern.size() - i - 1)) & 1;elseres |= pattern[i] == '+' ? 1 : 0;}return res;}}int main(){int n, m, cs = 0;vector<Patch *> V;bool flag[1 << 20];while (scanf("%d%d", &n, &m), n || m){printf("Product %d\n", ++cs);for (int i = 0; i < m; i++){Patch *p = new Patch();cin >> p->time >> p->from >> p->to;V.push_back(p);}priority_queue<pair<int, int>, vector<pair<int, int> >, cmp> Q;int begin = 0;memset(flag, 0, sizeof(flag));for (int i = 0; i < n; i++){begin <<= 1;begin |= 1;}Q.push(make_pair(0, begin));int time = 0;bool find = false;while (!Q.empty()){pair<int, int> p = Q.top();Q.pop();if (!p.second){time = p.first;find = true;break;}if (flag[p.second])continue;elseflag[p.second] = true;for (size_t i = 0; i < V.size(); i++)if (match(p.second, V[i]->from)){int res = patch(p.second, V[i]->to);Q.push(make_pair(p.first + V[i]->time, res));}}if (find)printf("Fastest sequence takes %d seconds.\n\n", time);elseputs("Bugs cannot be fixed.\n");for (size_t i = 0; i < V.size(); i++)delete V[i];V.clear();}return 0;}

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