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5.sortMerge.cpp
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5.sortMerge.cpp
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// time complexity: n log n
// not in-place sorting
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int arr[]={13,-3,-25,20,-3,-16,-23,18,20,-7,12,-5,-22,15,-4,7};
void display(int size){
int i;
for(i=0;i<size;i++){
cout<<arr[i]<<" ";
}
cout<<"\n";
}
void merge(int low,int mid, int high){
int left,right;
left = mid - low + 1;
right = high - mid;
int arr1[left],arr2[right];
int i,j,k;
//copy arrays
for(i=0;i<left;i++){
arr1[i]=arr[low+i];
}
for(j=0;j<right;j++){
arr2[j]=arr[mid+1+j];
}
//merge arrays
arr1[left+1]=-99999;
arr2[right+1]=-99999;
i=0;
j=0;
for(k=low; i<left && j<right;k++){
if(arr1[i]<=arr2[j]){
arr[k]=arr1[i];
i++;
}
else{
arr[k]=arr2[j];
j++;
}
}
//copy back remaining
while(i<left){
arr[k]=arr1[i];
i++;
k++;
}
while(j<right){
arr[k]=arr2[j];
j++;
k++;
}
display(high+1);
}
void mergeSort(int low, int high){
if(low<high){
int mid = floor((low+high)/2);
mergeSort(low,mid);
mergeSort(mid+1,high);
merge(low,mid,high);
}
}
int main(){
int size = sizeof(arr)/sizeof(arr[0]);
int low=0;
int high=size-1;
mergeSort(low,high);
return 0;
}