归并排序

src/MergeSort

@@ -0,0 +1,55 @@
+/**
+ * 归并排序
+ */
+public class MergeSort {
+    public static void merge(int [] a, int start, int median, int end){
+        int i;
+        int j;
+        int k;
+        int n1 = median - start + 1;
+        int n2 = end - median;
+        int[] L = new int[n1];
+        int[] R = new int[n2];
+        for (i = 0, k = start; i < n1; i++, k++){
+            L[i] = a[k];
+        }
+        for (i = 0, k = median + 1; i < n2; i++, k++){
+            R[i] = a[k];
+        }
+        for (k = start, i = 0, j = 0; i < n1 && j < n2; k++){
+            if (L[i] < R[j]) {
+                a[k] = L[i];
+                i++;
+            } else {
+                a[k] = R[j];
+                j++;
+            }
+        }
+        while (i < n1){
+            a[k] = L[i];
+            i++;
+            k++;
+        }
+        while (j < n2){
+            a[k] = R[j];
+            j++;
+            k++;
+        }
+    }
+    public static void mergeSort(int[] a, int start, int end){
+        if (start < end){
+            int median = (start + end) / 2;
+            mergeSort(a, start, median);
+            mergeSort(a, median + 1, end);
+            merge(a, start, median, end);
+        }
+    }
+
+    public static void main(String[] args){
+        int [] a = {9,2,5,3,10,1,4,8,0,7,6};
+        mergeSort(a, 0, a.length-1);
+        for (int anA : a) {
+            System.out.print(anA + " ");
+        }
+    }
+}