// MergeSort
package abc;
public class MergeSort {
public static void main(String[] args) {
int[] arr = { 12, 11, 13, 5, 6, 7 };
int n = arr.length;
mergeSort(arr, 0, n - 1);
for (int i = 0; i < n; i++)
System.out.print(arr[i] + " ");
}
public static void mergeSort(int[] a, int l, int r) {
if (l < r) {
int m = (l + r - 1) / 2;
mergeSort(a, l, m);
mergeSort(a, m + 1, r);
merge(a, l, m, r);
}
}
public static void merge(int[] arr, int l, int m, int r) {
int n1 = m - l + 1;
int n2 = r - m;
int L[] = new int[n1];
int R[] = new int[n2];
for (int i = 0; i < n1; ++i)
L[i] = arr[l + i];
for (int j = 0; j < n2; ++j)
R[j] = arr[m + 1 + j];
int i = 0, j = 0;
int k = l;
while (i < n1 && j < n2) {
if (L[i] <= R[j]) {
arr[k] = L[i];
i++;
} else {
arr[k] = R[j];
j++;
}
k++;
}
while (i < n1) {
arr[k] = L[i];
i++;
k++;
}
while (j < n2) {
arr[k] = R[j];
j++;
k++;
}
}
}