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Satisfiability.java
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Satisfiability.java
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import java.util.Scanner;
public class Satisfiability {
private static Integer []parents;
public static boolean equationsPossible(String[] equations) {
parents = new Integer[26];
//init parents to be parents to itselfs
for (int i = 0; i < parents.length; i++) {
parents[i]=i;
}
//go throught to all equations/nodes
for (int i = 0; i < equations.length; i++) {
String equation = equations[i];
if(isEquality(equation)){ // check if "==" ||| 97='a'
int indexval1 = getParent(equation.charAt(0)-97); // get the index of the char in parents
int indexval2 = getParent(equation.charAt(3)-97); // get the index of the char in parents
if(indexval1!=indexval2) parents[indexval1]=indexval2; // unify both edges
}
}
for (int i = 0; i < equations.length; i++) {
String equation = equations[i];
if(!isEquality(equation)){ // check if "!=" ||| 97='a'
int indexval1 = getParent(equation.charAt(0)-97); // get the index of the char in parents
int indexval2 = getParent(equation.charAt(3)-97); // get the index of the char in parents
if(isContradiction(indexval1,indexval2)) return false; // unify both edgese
}
}
return true;
}
private static int getParent(int i) {
if(parents[i]==i) return i;
return getParent(parents[i]);
}
public static boolean isEquality(String curr){
return curr.charAt(1)=='=';
}
public static boolean isContradiction(Integer indexval1,Integer indexval2){
return indexval1==indexval2;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String []arr = {"a==b","a==a","x==b","x!=a"};
System.out.println(equationsPossible(arr));
}
}