题目链接:https://vjudge.net/problem/UVA-213
题目翻译摘自《算法禁赛入门经典》
题目大意
考虑下面的 01 串序列:
0, 00, 01, 10, 000, 001, 010, 011, 100, 101, 110, 0000, 0001, …, 1101, 1110, 00000, …
首先是长度为 1 的串,然后是长度为 2 的串,依此类推。如果看成二进制,相同长度的后一个串等于前一个串加 1。注意上述序列中不存在全为 1 的串。
你的任务是编写一个解码程序。首先输入一个编码头(例如AB#TANCnrtXc),则上述序列的每个串依次对应编码头的每个字符。例如,0对应A,00对应B,01对应#,…,110对应X,0000对应c。接下来是编码文本(可能由多行组成,你应当把它们拼成一个长长的01串)。编码文本由多个小节组成,每个小节的前3个数字代表小节中每个编码的长度(用二进制表示,例如010代表长度为2),然后是各个字符的编码,以全1结束(例如,编码长度为2的小节以11结束)。编码文本以编码长度为000的小节结束。
例如,编码头为\$#**\,编码文本为0100000101101100011100101000,应这样解码:010(编码长度为2)00(#)00(#)10(*)11(小节结束)011(编码长度为3)000(\)111(小节结束)001(编码长度为1)0(\$)1(小节结束)000(编码结束)。
分析
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 < (n); ++i) 6 #define For(i,s,t) for (int i = (s); i <= (t); ++i) 7 #define rFor(i,t,s) for (int i = (t); i >= (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 21 #define ms0(a) memset(a,0,sizeof(a)) 22 #define msI(a) memset(a,inf,sizeof(a)) 23 #define msM(a) memset(a,-1,sizeof(a)) 24 25 #define MP make_pair 26 #define PB push_back 27 #define ft first 28 #define sd second 29 30 template<typename T1, typename T2> 31 istream &operator>>(istream &in, pair<T1, T2> &p) { 32 in >> p.first >> p.second; 33 return in; 34 } 35 36 template<typename T> 37 istream &operator>>(istream &in, vector<T> &v) { 38 for (auto &x: v) 39 in >> x; 40 return in; 41 } 42 43 template<typename T1, typename T2> 44 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) { 45 out << "[" << p.first << ", " << p.second << "]" << "\n"; 46 return out; 47 } 48 49 inline int gc(){ 50 static const int BUF = 1e7; 51 static char buf[BUF], *bg = buf + BUF, *ed = bg; 52 53 if(bg == ed) fread(bg = buf, 1, BUF, stdin); 54 return *bg++; 55 } 56 57 inline int ri(){ 58 int x = 0, f = 1, c = gc(); 59 for(; c<48||c>57; f = c=='-'?-1:f, c=gc()); 60 for(; c>47&&c<58; x = x*10 + c - 48, c=gc()); 61 return x*f; 62 } 63 64 template<class T> 65 inline string toString(T x) { 66 ostringstream sout; 67 sout << x; 68 return sout.str(); 69 } 70 71 typedef long long LL; 72 typedef unsigned long long uLL; 73 typedef pair< double, double > PDD; 74 typedef pair< int, int > PII; 75 typedef pair< int, PII > PIPII; 76 typedef pair< string, int > PSI; 77 typedef pair< int, PSI > PIPSI; 78 typedef set< int > SI; 79 typedef set< PII > SPII; 80 typedef vector< int > VI; 81 typedef vector< VI > VVI; 82 typedef vector< PII > VPII; 83 typedef map< int, int > MII; 84 typedef map< int, PII > MIPII; 85 typedef map< PII, int > MPIII; 86 typedef map< string, int > MSI; 87 typedef map< string, string > MSS; 88 typedef map< PII, string > MPIIS; 89 typedef multimap< int, int > MMII; 90 //typedef unordered_map< int, int > uMII; 91 typedef pair< LL, LL > PLL; 92 typedef vector< LL > VL; 93 typedef vector< VL > VVL; 94 typedef priority_queue< int > PQIMax; 95 typedef priority_queue< int, VI, greater< int > > PQIMin; 96 const double EPS = 1e-6; 97 const LL inf = 0x7fffffff; 98 const LL infLL = 0x7fffffffffffffffLL; 99 const LL mod = 1e9 + 7; 100 const int maxN = 1e4 + 7; 101 const LL ONE = 1; 102 const LL evenBits = 0xaaaaaaaaaaaaaaaa; 103 const LL oddBits = 0x5555555555555555; 104 105 string str; 106 char dic[8][1 << 8]; 107 108 inline int getInt(int n) { 109 int ret = 0; 110 char tmp; 111 while(n--) { 112 cin >> tmp; 113 if(tmp == '\r' || tmp == '\n') continue; 114 ret = ret * 2 + tmp - '0'; 115 } 116 return ret; 117 } 118 119 int main(){ 120 //freopen("MyOutput.txt","w",stdout); 121 //freopen("input.txt","r",stdin); 122 INIT(); // 有了这个就不能用getchar,printf和scanf等等了 123 while(getline(cin, str)) { 124 int x = 1, y = 0; 125 Rep(i, str.size()) { 126 if(y > (ONE << x) - 2) { 127 ++x; 128 y = 0; 129 } 130 dic[x][y++] = str[i]; 131 } 132 133 int len; 134 while(len = getInt(3)) { 135 while(1) { 136 int value = getInt(len); 137 if(!dic[len][value]) break; 138 cout << dic[len][value]; 139 } 140 } 141 cout << endl; 142 getline(cin, str); // 处理掉多余的尾巴 143 } 144 return 0; 145 }