我正在尝试基于维基百科伪代码实现 CYK 算法。当我测试语法输入的字符串“ab”时:
S->AB
一个->一个
B->b
它给了我虚假,我认为它应该是真实的。我有一个名为 AllGrammar 的数组列表,其中包含所有规则。对于上面的示例,它将包含:
[0]:S->AB
[1]:A->a
[2]:B->b
对于示例 S->hello 和输入字符串 hello 它给了我应有的真实感。更复杂的测试(更多产品)给了我错误:S
public static boolean cyk(String entrada) {
int n = entrada.length();
int r = AllGrammar.size();
//Vector<String> startingsymbols = getSymbols(AllGrammar);
String[] ent = entrada.split("\\s");
n = ent.length;
System.out.println("length of entry" + n);
//let P[n,n,r] be an array of booleans. Initialize all elements of P to false.
boolean P[][][] = initialize3DVector(n, r);
//n-> number of words of string entrada,
//r-> number of nonterminal symbols
//This grammar contains the subset Rs which is the set of start symbols
for (int i = 1; i < n; i++) {
for(int j = 0; j < r; j++) {
String[] rule = (String[]) AllGrammar.get(j);
if (rule.length == 2) {
if (rule[1].equals(ent[i])) {
System.out.println("entrou");
System.out.println(rule[1]);
P[i][1][j + 1] = true;
}
}
}
}
for(int i = 2; i < n; i++) {
System.out.println("FIRST:" + i);
for(int j = 1; j < n - i + 1; j++) {
System.out.println("SECOND:" + j);
for(int k = 1; k < i - 1; k++) {
System.out.println("THIRD:" + k);
for(int g = 0; g < r; g++) {
String[] rule = (String[]) AllGrammar.get(g);
if (rule.length > 2) {
int A = returnPos(rule[0]);
int B = returnPos(rule[1]);
int C = returnPos(rule[2]);
System.out.println("A" + A);
System.out.println("B" + B);
System.out.println("C" + C);
if (A!=-1 && B!=-1 && C!=-1) {
if (P[j][k][B] && P[j + k][i - k][C]) {
System.out.println("entrou2");
P[j][i][A] = true;
}
}
}
}
}
}
}
for(int x = 0; x < r; x++) {
if(P[1][n][x]) return true;
}
return false;
}