UVA 297 Quadtrees

待我称王封你为后i 2023-06-04 14:54 6阅读 0赞

题目链接：[https://vjudge.net/problem/UVA-297][https_vjudge.net_problem_UVA-297]

题意摘自《算法禁赛入门经典》

### 题目大意 ###

略。

### 分析 ###

先递归建树，然后 dfs 求答案。

### 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 set< int > SI;
    127 typedef stack< int > SKI;
    128 typedef deque< int > DQI;
    129 typedef queue< int > QI;
    130 typedef priority_queue< int > PQIMax;
    131 typedef priority_queue< int, VI, greater< int > > PQIMin;
    132 const double EPS = 1e-8;
    133 const LL inf = 0x7fffffff;
    134 const LL infLL = 0x7fffffffffffffffLL;
    135 const LL mod = 1e9 + 7;
    136 const int maxN = 1e4 + 7;
    137 const LL ONE = 1;
    138 const LL evenBits = 0xaaaaaaaaaaaaaaaa;
    139 const LL oddBits = 0x5555555555555555;
    140 
    141 struct QuadtreeNode {
    142     char type;
    143     int num;
    144     QuadtreeNode* nxt[4];
    145     
    146     QuadtreeNode(char tp) : type(tp) {
    147         Rep(i, 4) nxt[i] = nullptr;
    148     }
    149 };
    150 
    151 int N;
    152 string str1, str2;
    153 QuadtreeNode* root1 = nullptr;
    154 QuadtreeNode* root2 = nullptr;
    155 
    156 int build(QuadtreeNode* &rt, string &str, int p, int cnt) { // 要传指针的引用，不然建树的时候指针就不是树上的指针了 
    157     assert(p < str.size() && rt == nullptr);
    158     rt = new QuadtreeNode(str[p]);
    159     
    160     switch(str[p]) {
    161         case 'p':{
    162             ++p;
    163             rt->num = 0;
    164             Rep(i, 4) {
    165                 p = build(rt->nxt[i], str, p, cnt >> 2);
    166                 rt->num += rt->nxt[i]->num;
    167             }
    168             return p;
    169         }
    170         case 'f':{
    171             rt->num = cnt;
    172             return p + 1;
    173         }
    174         case 'e':{
    175             rt->num = 0;
    176             return p + 1;
    177         }
    178         default:{
    179             assert(false);
    180         }
    181     }
    182 }
    183 
    184 void clear(QuadtreeNode* &rt) {
    185     if(rt == nullptr) return;
    186     Rep(i, 4) {
    187         if(rt->nxt[i] != nullptr) {
    188             clear(rt->nxt[i]);
    189         }
    190     }
    191     delete rt;
    192     rt = nullptr;
    193 }
    194 
    195 int solve(QuadtreeNode* &rt1, QuadtreeNode* &rt2) {
    196     int ret = 0;
    197     
    198     if(rt1->type == 'p' && rt2->type == 'p') {
    199         Rep(i, 4) ret += solve(rt1->nxt[i], rt2->nxt[i]);
    200     }
    201     else ret = max(rt1->num, rt2->num);
    202     
    203     return ret;
    204 }
    205 
    206 int main() {
    207     //freopen("MyOutput.txt","w",stdout);
    208     //freopen("input.txt","r",stdin);
    209     //INIT();
    210     cin >> N;
    211     while(N--) {
    212         clear(root1);
    213         clear(root2);
    214         cin >> str1 >> str2;
    215         
    216         build(root1, str1, 0, 1024);
    217         build(root2, str2, 0, 1024);
    218         
    219         printf("There are %d black pixels.\n", solve(root1, root2));
    220     }
    221     return 0;
    222 }

转载于:https://www.cnblogs.com/zaq19970105/p/11390220.html

[https_vjudge.net_problem_UVA-297]: https://vjudge.net/problem/UVA-297
[ContractedBlock.gif]: https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif
[ExpandedBlockStart.gif]: /images/20230601/4a530fca99b1490cb5112cfb4be1f62a.png