Merging sort Merge Sorts

Merge (merge) sorting method is to combine two (or more than two) ordered tables into a new ordered table, that is, the ordered sequence is divided into several sub-sequences, each sub-sequence is ordered. Then the ordered subsequence is combined into a whole ordered sequence.

Merge sort is an efficient sorting algorithm based on the merging operation. This algorithm is a very typical application of the partition method (Divide and Conquer).

The ordered Subsequence is merged to obtain a fully ordered sequence, i.e., the order of each subsequence is ordered, and then the sequence of sub-sequences is ordered. If you combine two ordered tables into an ordered table, it is called a 2-way merge.

Example

Original state

First array [2 6]

Second array [1 4]

The third array of [...]

1th step, order from the first, the second array to take a number: 2 and 1

When the size is compared, the small one is placed in the third array, and this becomes the bottom

First array [2 6]

Second array [4]

Third Array [1]

2nd, proceed to the previous step, order from the first, the second array to fetch data, 2 and 4,

The same size will be small after the third array, the state as follows

First array [6]

Second array [4]

Third array [1 2]

3rd step, then repeat the previous step to change the smaller 4 into the third array after the following state

First array [6]

The second array of [...]

Third Array [1 2 4]

4th step, finally put 6, sorted

The first array of [...]

The second array of [...]

Third Array [1 2 4 6]

The Java code is as follows:

public class MergeSort {public static void main (string[] args) {//First two arrays are ordered arrays int[] data1 = {2, 6, 8, 10, 17};
		Int[] Data2 = {7, 9, 11, 14, 20};
		From small to large sort int[] Tempsmalltolarge = Smalltolarge (data1, data2);
		
		From large to small sort int[] Templargetosmall = Largetosmall (data1, data2); 
		Show (Tempsmalltolarge);
		System.out.println ("");
	Show (Templargetosmall); }//This method implements the merged array sort for small to large sort public static int[] Smalltolarge (int[] data1, int[] data2) {int[] temp = new Int[data1.leng
		th + data2.length];
		int i = 0, j = 0, iter = 0; for (; I < data1.length && J < Data2.length;)
				{if (Data1[i] <= data2[j]) {Temp[iter] = Data1[i];
				iter++;
			i++;
				}else {Temp[iter] = data2[j];
				iter++;
			j + +;
		}} for (; i < data1.length; i++, iter++) {Temp[iter] = Data1[i];
		} for (; J < Data2.length; J + +, iter++) {Temp[iter] = data2[j];
	} return temp; }//This method implements the sorting of the merged array from large to small sort public static int[] Largetosmall (int[] data1, int[] DaTA2) {int[] temp = new Int[data1.length + data2.length];
		int i = data1.length-1, j = data2.length-1, iter = 0; for (; I >= 0 && J >= 0;)
				{if (Data1[i] > Data2[j]) {Temp[iter] = Data1[i];
				iter++;
			i--;
				}else {Temp[iter] = data2[j];
				iter++;
			j--;
		}} for (; I >= 0; I--, iter++) {Temp[iter] = Data1[i];
		} for (; J >= 0; J--, iter++) {Temp[iter] = data2[j];
	} return temp;  }//auxiliary function public static void show (int[] temp) {for (int i = 0; i < temp.length; i++) {System.out.print (Temp[i]
		+ " ");
 }
	}
}