牛客 字符串的转换路径问题
题目大意:
略。
分析:
先建图,然后 bfs 算每个节点到终点的最短距离,最后用 dfs 输出。
代码如下:
1 #include <bits/stdc++.h> 2 using namespace std; 3 4 #define INIT() ios::sync_with_stdio(false);cin.tie(0);cout.tie(0); 5 #define Rep(i,n) for (int i = 0; i < (int)(n); ++i) 6 #define For(i,s,t) for (int i = (int)(s); i <= (int)(t); ++i) 7 #define rFor(i,t,s) for (int i = (int)(t); i >= (int)(s); --i) 8 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i) 9 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i) 10 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i) 11 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i) 12 13 #define pr(x) cout << #x << " = " << x << " " 14 #define prln(x) cout << #x << " = " << x << endl 15 16 #define LOWBIT(x) ((x)&(-x)) 17 18 #define ALL(x) x.begin(),x.end() 19 #define INS(x) inserter(x,x.begin()) 20 #define UNIQUE(x) x.erase(unique(x.begin(), x.end()), x.end()) 21 #define REMOVE(x, c) x.erase(remove(x.begin(), x.end(), c), x.end()); // 删去 x 中所有 c 22 #define TOLOWER(x) transform(x.begin(), x.end(), x.begin(),::tolower); 23 #define TOUPPER(x) transform(x.begin(), x.end(), x.begin(),::toupper); 24 25 #define ms0(a) memset(a,0,sizeof(a)) 26 #define msI(a) memset(a,0x3f,sizeof(a)) 27 #define msM(a) memset(a,-1,sizeof(a)) 28 29 #define MP make_pair 30 #define PB push_back 31 #define ft first 32 #define sd second 33 34 template<typename T1, typename T2> 35 istream &operator>>(istream &in, pair<T1, T2> &p) { 36 in >> p.first >> p.second; 37 return in; 38 } 39 40 template<typename T> 41 istream &operator>>(istream &in, vector<T> &v) { 42 for (auto &x: v) 43 in >> x; 44 return in; 45 } 46 47 template<typename T> 48 ostream &operator<<(ostream &out, vector<T> &v) { 49 Rep(i, v.size()) out << v[i] << " \n"[i == v.size() - 1]; 50 return out; 51 } 52 53 template<typename T1, typename T2> 54 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) { 55 out << "[" << p.first << ", " << p.second << "]" << "\n"; 56 return out; 57 } 58 59 inline int gc(){ 60 static const int BUF = 1e7; 61 static char buf[BUF], *bg = buf + BUF, *ed = bg; 62 63 if(bg == ed) fread(bg = buf, 1, BUF, stdin); 64 return *bg++; 65 } 66 67 inline int ri(){ 68 int x = 0, f = 1, c = gc(); 69 for(; c<48||c>57; f = c=='-'?-1:f, c=gc()); 70 for(; c>47&&c<58; x = x*10 + c - 48, c=gc()); 71 return x*f; 72 } 73 74 template<class T> 75 inline string toString(T x) { 76 ostringstream sout; 77 sout << x; 78 return sout.str(); 79 } 80 81 inline int toInt(string s) { 82 int v; 83 istringstream sin(s); 84 sin >> v; 85 return v; 86 } 87 88 //min <= aim <= max 89 template<typename T> 90 inline bool BETWEEN(const T aim, const T min, const T max) { 91 return min <= aim && aim <= max; 92 } 93 94 typedef unsigned int uI; 95 typedef long long LL; 96 typedef unsigned long long uLL; 97 typedef vector< int > VI; 98 typedef vector< bool > VB; 99 typedef vector< char > VC; 100 typedef vector< double > VD; 101 typedef vector< string > VS; 102 typedef vector< LL > VL; 103 typedef vector< VI > VVI; 104 typedef vector< VB > VVB; 105 typedef vector< VS > VVS; 106 typedef vector< VL > VVL; 107 typedef vector< VVI > VVVI; 108 typedef vector< VVL > VVVL; 109 typedef pair< int, int > PII; 110 typedef pair< LL, LL > PLL; 111 typedef pair< int, string > PIS; 112 typedef pair< string, int > PSI; 113 typedef pair< string, string > PSS; 114 typedef pair< double, double > PDD; 115 typedef vector< PII > VPII; 116 typedef vector< PLL > VPLL; 117 typedef vector< VPII > VVPII; 118 typedef vector< VPLL > VVPLL; 119 typedef vector< VS > VVS; 120 typedef map< int, int > MII; 121 typedef unordered_map< int, int > uMII; 122 typedef map< LL, LL > MLL; 123 typedef map< string, int > MSI; 124 typedef map< int, string > MIS; 125 typedef multiset< int > mSI; 126 typedef multiset< char > mSC; 127 typedef set< int > SI; 128 typedef stack< int > SKI; 129 typedef deque< int > DQI; 130 typedef queue< int > QI; 131 typedef priority_queue< int > PQIMax; 132 typedef priority_queue< int, VI, greater< int > > PQIMin; 133 const double EPS = 1e-8; 134 const LL inf = 0x7fffffff; 135 const LL infLL = 0x7fffffffffffffffLL; 136 const LL mod = 1e9 + 7; 137 const int maxN = 5e3 + 7; 138 const LL ONE = 1; 139 const LL evenBits = 0xaaaaaaaaaaaaaaaa; 140 const LL oddBits = 0x5555555555555555; 141 142 struct Edge { 143 int from; 144 int to; 145 146 Edge(int f, int t) : from(f), to(t){} 147 }; 148 149 struct Vertex { 150 int level; 151 VI nexts; 152 153 Vertex() { 154 level = -1; 155 nexts.clear(); 156 } 157 158 void clear() { 159 level = -1; 160 nexts.clear(); 161 } 162 }; 163 164 int N; 165 string S, T; 166 int idxS, idxT; 167 string arr[maxN]; 168 VVI ans; 169 VI res; 170 171 Vertex V[maxN]; 172 vector< Edge > E; 173 bool vis[maxN]; 174 175 void addEdge(Edge &x) { 176 V[x.from].nexts.PB(E.size()); 177 E.PB(x); 178 } 179 180 void init() { 181 ans.clear(); 182 res.clear(); 183 For(i, 1, N + 1) V[i].clear(); 184 E.clear(); 185 } 186 187 int calc(string &x, string &y) { 188 assert(x.size() == 3 && y.size() == 3); 189 190 int cnt = 0; 191 Rep(i, x.size()) if(x[i] != y[i]) ++cnt; 192 return cnt; 193 } 194 195 bool cmp(const int &x, const int &y) { 196 return arr[E[x].to] < arr[E[y].to]; 197 } 198 199 void build() { 200 For(i, 1, N) { 201 For(j, i + 1, N) { 202 int ret = calc(arr[i], arr[j]); 203 204 if(ret == 1) { 205 Edge t(i, j); 206 addEdge(t); 207 swap(t.from, t.to); 208 addEdge(t); 209 } 210 } 211 } 212 213 For(i, 1, N) sort(ALL(V[i].nexts), cmp); // 为了按照字典序输出 214 } 215 216 void bfs(int s) { 217 ms0(vis); 218 QI Q; 219 Q.push(s); 220 vis[s] = 1; 221 222 int cnt = 1; 223 int len = 1; 224 225 while(!Q.empty()) { 226 int tmp = Q.front(); Q.pop(); 227 --cnt; 228 229 V[tmp].level = len; 230 if(tmp == idxS) return; 231 232 Rep(i, V[tmp].nexts.size()) { 233 Edge &e = E[V[tmp].nexts[i]]; 234 235 if(vis[e.to]) continue; 236 vis[e.to] = 1; 237 Q.push(e.to); 238 } 239 240 if(cnt == 0) { 241 cnt = Q.size(); 242 ++len; 243 } 244 } 245 } 246 247 void dfs(int s) { 248 if(s == idxT) { 249 ans.PB(res); 250 return; 251 } 252 253 Rep(i, V[s].nexts.size()) { 254 Edge &e = E[V[s].nexts[i]]; 255 256 if(V[e.to].level != V[s].level - 1) continue; 257 res.PB(e.to); 258 dfs(e.to); 259 res.pop_back(); 260 } 261 } 262 263 void printAns() { 264 if(ans.empty()) cout << "NO\n"; 265 else { 266 cout << "YES\n"; 267 Rep(i, ans.size()) { 268 Rep(j, ans[i].size()) { 269 if(j) cout << " -> "; 270 cout << arr[ans[i][j]]; 271 } 272 cout << endl; 273 } 274 } 275 } 276 277 int main() { 278 //freopen("MyOutput.txt","w",stdout); 279 //freopen("input.txt","r",stdin); 280 //INIT(); 281 while(cin >> N >> S >> T) { 282 init(); 283 284 For(i, 1, N) { // 输入无重复 285 cin >> arr[i]; 286 if(T == arr[i]) idxT = i; 287 } 288 289 arr[++N] = S; 290 idxS = N; 291 build(); // 建图 292 293 bfs(idxT); // bfs构建最短路路标 294 res.PB(idxS); 295 dfs(idxS); // dfs按照路标输出最短路 296 297 printAns(); 298 } 299 return 0; 300 }