归并排序算法
1. import java.util.Arrays;
2.
3. /**
4. * java归并算法实现<br>
5. *
6. * @author JAVA世纪网(java2000.net, laozizhu.com)
7. */
8. public class Test {
9. final static int MAXVALUE = 10000;
10.
11. static int[] L;
12.
13. static int[] R;
14.
15. public static void Merge(int[] A, int p, int q, int r) {
16. int n1 = q - p;
17. int n2 = r - q + 1;
18. L = new int[n1 + 1];
19. R = new int[n2 + 1];
20. for (int i = 0; i < n1; i++) {
21. L[i] = A[p + i];
22. }
23. for (int j = 0; j < n2; j++) {
24. R[j] = A[q + j];
25. }
26. L[n1] = MAXVALUE;
27. R[n2] = MAXVALUE;
28. int i = 0, j = 0;
29. for (int k = p; k <= r; k++) {
30. if (L[i] <= R[j]) {
31. A[k] = L[i];
32. i++;
33. } else {
34. A[k] = R[j];
35. j++;
36. }
37. }
38. }
39.
40. public static void MergeSort(int[] A, int p, int r) {
41. int q;
42. if (p < r) {
43. q = (p + r) / 2;
44. MergeSort(A, p, q);
45. MergeSort(A, q + 1, r);
46. Merge(A, p, q + 1, r);
47. }
48. }
49.
50. public static void main(String[] args) {
51. int[] inputArray = { 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4, 7, 1,
52. 3 };
53. // 方法1
54. MergeSort(inputArray, 0, inputArray.length - 1);
55. System.out.println(Arrays.toString(inputArray));
56. Integer[] inputArray2 = { 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4,
57. 7, 1, 3 };
58. // 方法2
59. new MergeSort().sort(inputArray2);
60. System.out.println(Arrays.toString(inputArray2));
61. }
62. }
63.
64. class MergeSort {
65. private Comparable[] bridge;
66.
67. /**
68. * *利用归并排序算法对数组obj进行排序
69. */
70. public void sort(Comparable[] obj) {
71. if (obj == null) {
72. throw new NullPointerException("The param can not be null!");
73. }
74. bridge = new Comparable[obj.length];// 初始化中间数组
75. mergeSort(obj, 0, obj.length - 1); // 归并排序
76. bridge = null;
77. }
78.
79. /**
80. * 将下标从left到right的数组进行归并排序
81. *
82. * @param obj 要排序的数组的句柄
83. * @param left 要排序的数组的第一个元素下标
84. * @param right 要排序的数组的最后一个元素的下标
85. */
86. private void mergeSort(Comparable[] obj, int left, int right) {
87. if (left < right) {
88. int center = (left + right) / 2;
89. mergeSort(obj, left, center);
90. mergeSort(obj, center + 1, right);
91. merge(obj, left, center, right);
92. }
93. }
94.
95. /**
96. * *将两个对象数组进行归并，并使归并后为升序。归并前两个数组分别有序
97. *
98. * @param obj 对象数组的句柄
99. * @param left 左数组的第一个元素的下标
100. * @param center 左数组的最后一个元素的下标
101. * @param right 右数组的最后一个元素的下标
102. */
103. private void merge(Comparable[] obj, int left, int center, int right) {
104. int mid = center + 1;
105. int third = left;
106. int tmp = left;
107. while (left <= center && mid <= right) { // 从两个数组中取出小的放入中间数组
108. if (obj[left].compareTo(obj[mid]) <= 0) {
109. bridge[third++] = obj[left++];
110. } else
111. bridge[third++] = obj[mid++];
112. }
113. // 剩余部分依次置入中间数组
114. while (mid <= right) {
115. bridge[third++] = obj[mid++];
116. }
117. while (left <= center) {
118. bridge[third++] = obj[left++];
119. }
120. // 将中间数组的内容拷贝回原数组
121. copy(obj, tmp, right);
122. }
123.
124. /**
125. * *将中间数组bridge中的内容拷贝到原数组中
126. *
127. * @param obj 原数组的句柄
128. * @param left 要拷贝的第一个元素的下标
129. * @param right 要拷贝的最后一个元素的下标
130. */
131. private void copy(Comparable[] obj, int left, int right) {
132. while (left <= right) {
133. obj[left] = bridge[left];
134. left++;
135. }
136. }
137. }
2.
3. /**
4. * java归并算法实现<br>
5. *
6. * @author JAVA世纪网(java2000.net, laozizhu.com)
7. */
8. public class Test {
9. final static int MAXVALUE = 10000;
10.
11. static int[] L;
12.
13. static int[] R;
14.
15. public static void Merge(int[] A, int p, int q, int r) {
16. int n1 = q - p;
17. int n2 = r - q + 1;
18. L = new int[n1 + 1];
19. R = new int[n2 + 1];
20. for (int i = 0; i < n1; i++) {
21. L[i] = A[p + i];
22. }
23. for (int j = 0; j < n2; j++) {
24. R[j] = A[q + j];
25. }
26. L[n1] = MAXVALUE;
27. R[n2] = MAXVALUE;
28. int i = 0, j = 0;
29. for (int k = p; k <= r; k++) {
30. if (L[i] <= R[j]) {
31. A[k] = L[i];
32. i++;
33. } else {
34. A[k] = R[j];
35. j++;
36. }
37. }
38. }
39.
40. public static void MergeSort(int[] A, int p, int r) {
41. int q;
42. if (p < r) {
43. q = (p + r) / 2;
44. MergeSort(A, p, q);
45. MergeSort(A, q + 1, r);
46. Merge(A, p, q + 1, r);
47. }
48. }
49.
50. public static void main(String[] args) {
51. int[] inputArray = { 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4, 7, 1,
52. 3 };
53. // 方法1
54. MergeSort(inputArray, 0, inputArray.length - 1);
55. System.out.println(Arrays.toString(inputArray));
56. Integer[] inputArray2 = { 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4, 7, 1, 3, 2, 6, 5, 2, 4,
57. 7, 1, 3 };
58. // 方法2
59. new MergeSort().sort(inputArray2);
60. System.out.println(Arrays.toString(inputArray2));
61. }
62. }
63.
64. class MergeSort {
65. private Comparable[] bridge;
66.
67. /**
68. * *利用归并排序算法对数组obj进行排序
69. */
70. public void sort(Comparable[] obj) {
71. if (obj == null) {
72. throw new NullPointerException("The param can not be null!");
73. }
74. bridge = new Comparable[obj.length];// 初始化中间数组
75. mergeSort(obj, 0, obj.length - 1); // 归并排序
76. bridge = null;
77. }
78.
79. /**
80. * 将下标从left到right的数组进行归并排序
81. *
82. * @param obj 要排序的数组的句柄
83. * @param left 要排序的数组的第一个元素下标
84. * @param right 要排序的数组的最后一个元素的下标
85. */
86. private void mergeSort(Comparable[] obj, int left, int right) {
87. if (left < right) {
88. int center = (left + right) / 2;
89. mergeSort(obj, left, center);
90. mergeSort(obj, center + 1, right);
91. merge(obj, left, center, right);
92. }
93. }
94.
95. /**
96. * *将两个对象数组进行归并，并使归并后为升序。归并前两个数组分别有序
97. *
98. * @param obj 对象数组的句柄
99. * @param left 左数组的第一个元素的下标
100. * @param center 左数组的最后一个元素的下标
101. * @param right 右数组的最后一个元素的下标
102. */
103. private void merge(Comparable[] obj, int left, int center, int right) {
104. int mid = center + 1;
105. int third = left;
106. int tmp = left;
107. while (left <= center && mid <= right) { // 从两个数组中取出小的放入中间数组
108. if (obj[left].compareTo(obj[mid]) <= 0) {
109. bridge[third++] = obj[left++];
110. } else
111. bridge[third++] = obj[mid++];
112. }
113. // 剩余部分依次置入中间数组
114. while (mid <= right) {
115. bridge[third++] = obj[mid++];
116. }
117. while (left <= center) {
118. bridge[third++] = obj[left++];
119. }
120. // 将中间数组的内容拷贝回原数组
121. copy(obj, tmp, right);
122. }
123.
124. /**
125. * *将中间数组bridge中的内容拷贝到原数组中
126. *
127. * @param obj 原数组的句柄
128. * @param left 要拷贝的第一个元素的下标
129. * @param right 要拷贝的最后一个元素的下标
130. */
131. private void copy(Comparable[] obj, int left, int right) {
132. while (left <= right) {
133. obj[left] = bridge[left];
134. left++;
135. }
136. }
137. }
