I’m making a game and want to implement cheat codes like the Konami code.
But how do I check for that sequence of keystrokes?
I want it to work so that if a player just types the code it will trigger.
Thanks in advance!
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Answer
Below is a class that checks for the Konami code, including cases such as “UP, UP, UP, DOWN, etc.”
This should work for any given sequence.
JavaScript
x
import java.util.Map;
import java.util.TreeMap;
public class Konami {
static private int[] code =
{UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, B};
static private Map<Integer, Integer>[] graph;
static private int currentNode = 0;
public static void main(String args[]) {
//Create graph
graph = generateSequenceMap(code);
//Call checkKonami(key) whenever a key is pressed
}
static public boolean checkKonami(int keyPressed) {
Integer nextNode = graph[currentNode].get(keyPressed);
//Set currentNode to nextNode or to 0 if no matching sub-sequence exists
currentNode = (nextNode==null ? 0 : nextNode);
return currentNode == code.length-1;
}
static private Map<Integer, Integer>[] generateSequenceMap(int[] sequence) {
//Create map
Map<Integer, Integer>[] graph = new Map[sequence.length];
for(int i=0 ; i<sequence.length ; i++) {
graph[i] = new TreeMap<Integer,Integer>();
}
//i is delta
for(int i=0 ; i<sequence.length ; i++) {
loop: for(int j=i ; j<sequence.length-1 ; j++) {
if(sequence[j-i] == sequence[j]) {
System.out.println("If at Node "+j+" you give me seq["+(j-i+1)
+ "] OR " + (sequence[j-i+1]) + " , goto Node " + (j-i+1));
//Ensure that the longest possible sub-sequence is recognized
Integer value = graph[j].get(sequence[j-i+1]);
if(value == null || value < j-i+1)
graph[j].put(sequence[j-i+1], j-i+1);
}
else
break loop;
}
}
return graph;
}
}