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MergeIn2048.java
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MergeIn2048.java
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package main.java.kyu5;
/**
* 5 kyu - Merge in 2048
*
* https://www.codewars.com/kata/55e1990978c60e5052000011
*
* Details:
*
* Remember the game 2048?
*
* The main part of this game is merging identical tiles in a row.
*
* Implement a function that models the process of merging all of the tile values in a single
* row.
* This function takes the array line as a parameter and returns a new array with the tile
* values from line slid towards the front of the array (index 0) and merged.
*
* A given tile can only merge once.
* Empty grid squares are represented as zeros.
* Your function should work on arrays containing arbitrary number of elements.
*/
import org.junit.Test;
import static org.junit.Assert.assertArrayEquals;
public class MergeIn2048 {
public static int[] merge(int[] line) {
if (line == null || line.length == 0) {
return new int[0];
}
compress(line);
final boolean isMerged = add(line);
if (isMerged) {
compress(line);
}
return line;
}
private final static void compress(int[] row) {
for (int i = 0; i < row.length; i++) {
if (row[i] == 0) {
for (int j = i; j < row.length; j++) {
if (row[j] != 0) {
row[i] = row[j];
row[j] = 0;
break;
}
}
}
}
}
private final static boolean add(int[] row) {
boolean isMerged = false;
for (int i = 0; i < row.length-1 ; i++) {
if (row[i] == row[i + 1] && row[i] != 0) {
row[i] = row[i] * 2;
row[i+1] = 0;
i++;
isMerged = true;
}
}
return isMerged;
}
@Test
public void sampleTests() {
assertArrayEquals(new int[] {4,2,0,0}, merge(new int[] {2,0,2,2}));
assertArrayEquals(new int[] {4,4,0,0}, merge(new int[] {2,0,2,4}));
assertArrayEquals(new int[] {4,0,0,0}, merge(new int[] {0,0,2,2}));
}
}