牛客字符串的转换路径问题

深碍√TFBOYSˉ_ 2023-06-04 14:55 19阅读 0赞

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][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： ###

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][]

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 }

转载于:https://www.cnblogs.com/zaq19970105/p/11417025.html

[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]: 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
[ContractedBlock.gif]: https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif
[ExpandedBlockStart.gif]: /images/20230601/21ad573a03204c559256b0a8413da182.png