标签：obj online arrays 算数 static boolean int ati bool
链接：
https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=3371
题意：
可以用表达式树来表示一个表达式。在本题中，运算符均为二元的，且运算符和运算数均用1～4个小写字母表示。
例如，a(b(f(a,a),b(f(a,a),f)),f(b(f(a,a),b(f(a,a),f)),f))可以表示为a(b(f(a,4),b(3,f)),f(2,6))，
其中各个结点按照出现顺序编号为1，2，3，…，即编号k表示目前为止写下的第k个结点。
输入一个长度不超过50000的表达式，输出一个等价的，结点最少的图。
分析：
用一个map把子树映射成编号1, 2,…。这样一来，子树就可以用根的名字（字符串）和左右子结点编号表示。
然后构造表达式树并判断地输出即可。
代码：
1 //HashMap version 2 import java.io.*; 3 import java.util.*; 4 import static java.util.Arrays.*; 5 import static java.lang.Character.*; 6 7 class Node { 8 String s; 9 int lch, rch; 10 11 @Override 12 public int hashCode() { 13 final int prime = 31; 14 int result = 1; 15 result = prime * result + lch; 16 result = prime * result + rch; 17 result = prime * result + ((s == null) ? 0 : s.hashCode()); 18 return result; 19 } 20 21 @Override 22 public boolean equals(Object obj) { 23 if (this == obj) 24 return true; 25 if (obj == null) 26 return false; 27 if (getClass() != obj.getClass()) 28 return false; 29 Node other = (Node) obj; 30 if (lch != other.lch) 31 return false; 32 if (rch != other.rch) 33 return false; 34 if (s == null) { 35 if (other.s != null) 36 return false; 37 } else if (!s.equals(other.s)) 38 return false; 39 return true; 40 } 41 } 42 43 public class Main { 44 Scanner cin = new Scanner(new BufferedInputStream(System.in)); 45 final int UP = 50000 + 5; 46 int p, nextNode; 47 char s[]; 48 boolean vis[] = new boolean[UP]; 49 Node node[] = new Node[UP]; 50 HashMap<Node,Integer> map = new HashMap<Node,Integer>(); 51 52 { for(int i = 0; i < UP; i++) node[i] = new Node(); } 53 54 int parse() { 55 int id = ++nextNode; 56 node[id].s = ""; 57 node[id].lch = node[id].rch = 0; 58 while(isLetter(s[p])) { 59 node[id].s += s[p]; 60 p++; 61 } 62 if(s[p] == ‘(‘) { 63 p++; node[id].lch = parse(); p++; node[id].rch = parse(); p++; 64 } 65 if(map.containsKey(node[id])) { 66 nextNode--; 67 return map.get(node[id]); 68 } 69 map.put(node[id], id); 70 return id; 71 } 72 73 void output(int id) { 74 if(vis[id]) { 75 System.out.print(id); 76 return; 77 } 78 vis[id] = true; 79 System.out.print(node[id].s); 80 if(node[id].lch != 0) { 81 System.out.print(‘(‘); 82 output(node[id].lch); 83 System.out.print(‘,‘); 84 output(node[id].rch); 85 System.out.print(‘)‘); 86 } 87 } 88 89 void MAIN() { 90 int T = cin.nextInt(); 91 while(T --> 0) { 92 s = (cin.next() + "\0").toCharArray(); 93 p = nextNode = 0; 94 fill(vis, false); 95 map.clear(); 96 output(parse()); 97 System.out.println(); 98 } 99 } 100 101 public static void main(String args[]) { new Main().MAIN(); } 102 }
1 //TreeMap version 2 import java.io.*; 3 import java.util.*; 4 import static java.util.Arrays.*; 5 import static java.lang.Character.*; 6 7 class Node implements Comparable<Node> { 8 String s; 9 int hash, lch, rch; 10 11 @Override 12 public int compareTo(Node that) { 13 if(hash != that.hash) return hash - that.hash; 14 if(lch != that.lch) return lch - that.lch; 15 return rch - that.rch; 16 } 17 } 18 19 public class Main { 20 Scanner cin = new Scanner(new BufferedInputStream(System.in)); 21 final int UP = 50000 + 5; 22 int p, nextNode; 23 char s[]; 24 boolean vis[] = new boolean[UP]; 25 Node node[] = new Node[UP]; 26 TreeMap<Node,Integer> map = new TreeMap<Node,Integer>(); 27 28 { for(int i = 0; i < UP; i++) node[i] = new Node(); } 29 30 int parse() { 31 int id = ++nextNode; 32 node[id].s = ""; 33 node[id].hash = node[id].lch = node[id].rch = 0; 34 while(isLetter(s[p])) { 35 node[id].hash = node[id].hash * 29 + s[p] - ‘a‘ + 1; 36 node[id].s += s[p]; 37 p++; 38 } 39 if(s[p] == ‘(‘) { 40 p++; node[id].lch = parse(); p++; node[id].rch = parse(); p++; 41 } 42 if(map.containsKey(node[id])) { 43 nextNode--; 44 return map.get(node[id]); 45 } 46 map.put(node[id], id); 47 return id; 48 } 49 50 void output(int id) { 51 if(vis[id]) { 52 System.out.print(id); 53 return; 54 } 55 vis[id] = true; 56 System.out.print(node[id].s); 57 if(node[id].lch != 0) { 58 System.out.print(‘(‘); 59 output(node[id].lch); 60 System.out.print(‘,‘); 61 output(node[id].rch); 62 System.out.print(‘)‘); 63 } 64 } 65 66 void MAIN() { 67 int T = cin.nextInt(); 68 while(T --> 0) { 69 s = (cin.next() + "\0").toCharArray(); 70 p = nextNode = 0; 71 fill(vis, false); 72 map.clear(); 73 output(parse()); 74 System.out.println(); 75 } 76 } 77 78 public static void main(String args[]) { new Main().MAIN(); } 79 }
UVa 12219 - Common Subexpression Elimination
标签：obj online arrays 算数 static boolean int ati bool
原文地址：https://www.cnblogs.com/hkxy125/p/9074850.html
