牛客 字符串的转换路径问题

题目链接:https://www.nowcoder.com/practice/9939decf61a748d1877774095ecd5ed2?tpId=101&tqId=33191&tPage=1&rp=1&ru=/ta/programmer-code-interview-guide&qru=/ta/programmer-code-interview-guide/question-ranking

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 }
View Code

 

posted @ 2019-08-27 11:01  梦樱羽  阅读(479)  评论(0编辑  收藏  举报
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