USACO 4.3 Letter game
2012-01-23 10:54
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今天年初一,到邻居和临近亲戚家转完回来接着做昨晚未写完的USACO 4.3 letter game,此题给出的字典最多有40000个单词,但是仔细算一下可以发现有很多用处不大,我们来看一下:由于最多只给出7个字母,最少也要给出3个,每个单词也是这个样子(这两个条件非常关键),所以如果出现pair words,那么只有2种情况——长度3的单词+长度3的单词,长度3+长度4。而长度为4的合法单词最多只有7^4=2401个,所以在查找pair words时大部分单词是可以被筛掉的。一个单词的情况当然非常简单了,扫描一下就可以了。注意给出的单词不必全都用上,因为这里WA了= =。此题作为新年为自己奉上的一个礼物吧,呵呵,虽然是个小水题。
/* ID: zlqest11 LANG: C++ TASK: lgame */ #include <iostream> #include <cstdio> #include <cstring> #include <vector> #include <algorithm> using namespace std; const int N = 40005; const int pv[26] = {2,5,4,4,1,6,5,5,1,7,6,3,5,2,3,5,7,2,1,2,4,6,6,7,5,7}; struct node{ int first, second; node(){ first = second = 0; } node(int x, int y){ first = x, second = y; } }; char latter[10], dic [10]; int n, len, val ; int ct[26], tmp[26]; vector <int> hash3[50], hash4[50]; vector <node> res; bool cmp(const node &a, const node &b){ int x = strcmp(dic[a.first], dic[b.first]); int y = strcmp(dic[a.second], dic[b.second]); if(x == 0) return y < 0; else return x < 0; } int getVal(const char * str){ int ans = 0, len = strlen(str); for(int i = 0; i < len; i++) ans += pv[str[i]-'a']; return ans; } bool check(const char * str){ for(int i = 0; str[i]; i++){ bool flag = false; for(int j = 0; j < len; j++) if(str[i] == latter[j]){ flag = true; break; } if(!flag) return false; } return true; } bool Yes(int x, int y){ memset(tmp, 0, sizeof(tmp)); int lx, ly; lx = strlen(dic[x]); ly = strlen(dic[y]); for(int i = 0; i < lx; i++) tmp[dic[x][i]-'a']++; for(int i = 0; i < ly; i++) tmp[dic[y][i]-'a']++; for(int i = 0; i < 26; i++) if(ct[i] < tmp[i]) return false; return true; } void fuc(const char * str, int pos){ int ans = 0, len = strlen(str); if(!(len==3 || len==4)) return; ans = val[pos]; if(len == 3) hash3[ans].push_back(pos); if(len == 4) hash4[ans].push_back(pos); } int main() { char str[10]; //read letter set freopen("lgame.in", "r", stdin); scanf("%s", latter); len = strlen(latter); memset(ct, 0, sizeof(ct)); for(int i = 0; i < len; i++){ ct[latter[i]-'a']++; } fclose(stdin); freopen("lgame.dict", "r", stdin); freopen("lgame.out", "w", stdout); //init the dic n = 0; while(~scanf("%s", str)){ if(strcmp(str, ".") == 0) break; else if(check(str)){ ++n; strcpy(dic , str); val = getVal(dic ); } } //init hash for(int i = 0; i < 50; i++){ hash3[i].clear(); hash4[i].clear(); } strcpy(dic[0], ""); for(int i = 1; i <= n; i++) fuc(dic[i], i); int ans; bool flag = false; //find ans and generate case for(ans = 49; ans >= 0; ans--){ for(int i = 1; i <= n; i++){ if(Yes(i, 0) && val[i]==ans){ flag = true; res.push_back(node(i, 0)); } } for(int i = 1; i <= ans; i++) if(hash3[i].size() != 0){ int index = ans-i; if(len==7 && hash4[index].size()!=0){ for(int p = 0; p < hash3[i].size(); p++) for(int q = 0; q < hash4[index].size(); q++){ if(Yes(hash3[i][p], hash4[index][q])){ res.push_back(node(hash3[i][p], hash4[index][q])); flag = true; } } } if(len>=6 && hash3[index].size()!=0){ for(int p = 0; p < hash3[i].size(); p++) for(int q = 0; q < hash3[index].size(); q++){ if(Yes(hash3[i][p], hash3[index][q])){ res.push_back(node(hash3[i][p], hash3[index][q])); flag = true; } } } } if(flag) break; } for(int i = 0; i < res.size(); i++){ if(res[i].second == 0) continue; else{ if(strcmp(dic[res[i].first], dic[res[i].second]) > 0) swap(res[i].first, res[i].second); } } sort(res.begin(), res.end(), cmp); printf("%d\n", ans); for(int i = 0; i < res.size(); i++){ if(i && res[i].first==res[i-1].first && res[i].second==res[i-1].second) continue; if(res[i].second == 0) printf("%s\n", dic[res[i].first]); else printf("%s %s\n", dic[res[i].first], dic[res[i].second]); } return 0; }
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