Merge Sort

Author: SeongHo5356

Merge_Sort.cpp

@@ -1,55 +1,62 @@
-#include <stdio.h>
+#include<iostream>
+#include<algorithm>
 
-int number = 10;
-int data[10] = {2,4,1,3,8,5,9,7,6,10};
+using namespace std;
 
-void quickSort(int *data, int start, int end ){
-	if(start >= end){ // 원소가 1개인 경우
-		return;
-	}
-	
-	int key = start; // 키는 첫번째 원소
-	int i = start + 1;
-	int j = end;
-	int temp;
-	
-	while(i <= j){ //엇갈릴 때까지 반복
-		while(data[i] <= data[key]){
+int number = 8;
+int sorted[8]; // 정렬 배열은 반드시 전역변수로 선언
+
+void merge(int a[], int begin, int middle, int end){
+	int i = begin;
+	int j = middle+1;
+	int k = begin;
+	//작은 순서대로 배열에 삽입 =
+	while(i<=middle && j <= end){
+		if(a[i]<=a[j]){
+			sorted[k]=a[i];
 			i++;
 		}
-		while(data[j] >= data[key] && j > start){
-			j--;
+		else{
+			sorted[k]=a[j];
+			j++;
 		}
-		if(i > j){ // 현재 엇갈린 상태면 키 값과 교체
-			temp = data[j];
-			data[j] = data[key];
-			data[key] = temp;
-		} else {
-			temp = data[j];
-			data[j] = data[i];
-			data[i] = temp;
+		k++;
+	}
+	//남은 데이터도 삽입
+	if( i > middle){
+		for(int t=j; t<=end; t++){
+			sorted[k] = a[t];
+			k++;
+		}
+	}
+	else{
+		for(int t=i; t<=middle; t++){
+			sorted[k] = a[t];
+			k++;
 		}
 	}
-	quickSort(data, start, j-1);
-	quickSort(data, j+1, end);
 
+	for(int t=begin; t<=end; t++){
+		a[t] = sorted[t];
+	}
 }
 
-int main(void){
-
-	// 정렬전 리스트의 모습    
-    for(int i=0; i<10; i++){
-    	printf("%d ",data[i]);
+void mergeSort(int a[], int m, int n){
+	if(m<n){
+		int middle = (m+n)/2;
+		mergeSort(a, m, middle);
+		mergeSort(a, middle+1,n);
+		merge(a, m, middle, n);
 	}
-	printf("\n");
-    
-    // 정렬 과정
-    quickSort(data, 0, number-1); 
+}
 
-    //정렬 후 리스트의 모습
-    for(int i=0;i<10; i++){
-    	printf("%d ",data[i]);
+int main(void){
+	int array[number] = {1,3,2,5,6,4,7,8};
+	mergeSort(array,0,number-1);
+	
+	for(int i=0;i<number;i++){
+		cout << array[i]<< ' '; 
 	}
-    
-    return 0;
+	
+	return 0;
 }

Merge_Sort.exe

@@ -0,0 +1,60 @@
+#include<algorithm>
+#include<iostream>
+
+using namespace std;
+
+int number = 8;
+int sorted[8];
+
+void merge(int a[], int start, int middle , int end){
+	int i = start;
+	int j = middle +1;
+	int k = start;
+	while(i<=middle && j<= end){
+		if(a[i] <= a[j]){
+			sorted[k] = a[i];
+			i++;
+		}
+		else{
+			sorted[k] = a[j];
+			j++;
+		}
+		k++;
+	}
+	if(i>middle){
+		for(int t=j; t<=end; t++){
+			sorted[k] = a[t];
+			k++;
+		}
+	}
+	else{
+		for(int t = i; t<=middle; t++){
+			sorted[k] = a[t];
+			k++;
+		}
+	}
+	
+	for(int i =start; i<= end; i++){
+		a[i] = sorted[i];
+	}
+}
+
+void mergeSort(int a[], int start, int end){
+	if(start < end){
+		int middle = (start + end)/2;
+		mergeSort(a, start, middle);
+		mergeSort(a, middle+1, end);
+		merge(a, start, middle, end);
+	}
+}
+
+int main(void){
+	int array[number] = {1,3,2,5,6,4,7,8};
+	mergeSort(array,0,number-1);
+	
+	for(int i=0;i<number;i++){
+		cout << array[i]<< ' '; 
+	}
+	
+	return 0;
+}