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56 lines (43 loc) · 1.55 KB
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Copy pathMergeSort.java
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56 lines (43 loc) · 1.55 KB
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package sort;
public class MergeSort {
public int[] sort(int[] arr) {
return mergeSort(arr);
}
private int[] mergeSort(final int[] array) {
if (array.length <= 1) {
return array;
}
final int midpoint = array.length / 2;
int[] left = new int[midpoint];
int[] right = new int[array.length - midpoint];
for (int i = 0; i < left.length; i++) {
left[i] = array[i];
}
for (int j = 0; j < right.length; j++) {
right[j] = array[midpoint + j];
}
left = mergeSort(left);
right = mergeSort(right);
return merge(left, right);
}
private int[] merge(final int[] left, final int[] right) {
final int[] result = new int[left.length + right.length];
int leftPointer = 0;
int rightPointer = 0;
int resultPointer = 0;
while (leftPointer < left.length || rightPointer < right.length) {
if (leftPointer < left.length && rightPointer < right.length) {
if (left[leftPointer] < right[rightPointer]) {
result[resultPointer++] = left[leftPointer++];
} else {
result[resultPointer++] = right[rightPointer++];
}
} else if (leftPointer < left.length) {
result[resultPointer++] = left[leftPointer++];
} else if (rightPointer < right.length) {
result[resultPointer++] = right[rightPointer++];
}
}
return result;
}
}