Merge sort

merge.md

###Merge sort

    #include <iostream>
    #include <vector>
    #include <algorithm>
    
    using namespace std;
    void merge(vector<int>& array,int left,int pivot,int right){
    	int leftLen = pivot - left + 1;
    	int rightLen = right - pivot;
    
    	vector<int> L(leftLen);
    	vector<int> R(rightLen);
    	int i,j;
    	for(i = 0; i < leftLen; ++i){
    		L[i] = array[left + i];
    	}
    	for(j = 0; j < rightLen; ++j){
    		R[j] = array[pivot + 1 + j];
    	}
    	int k = left;
    	for(i = 0,j = 0; i < leftLen && j < rightLen; ++k){
    		if(L[i] < R[j]){
    			array[k] = L[i++];
    		}else{
    			array[k] = R[j++];
    		}
    	}
    	if(i < leftLen){
    		for(; i < leftLen; ++i,++k){
    			array[k] = L[i];
    		}
    	}
    	if(j < rightLen){
    		for(; j < rightLen; ++k,++j){
    			array[k] = R[j];
    		}
    	}
    }
    void merge_sort(vector<int>& array,int left,int right){
    	if(left < right){
    		int q = left + ((right - left)>>1);
    		merge_sort(array,left,q);
    		merge_sort(array,q+1,right);
    		merge(array,left,q,right);
    	}
    }
    void print(vector<int>& array){
    	for(int i = 0; i < array.size(); ++i){
    		cout<<array[i]<<" ";
    	}
    	cout<<endl;
    }
    int main(){
    	vector<int> Test;
    	for(int i = 0; i < 20; ++i){
    		Test.push_back(i);
    	}
    	random_shuffle(Test.begin(),Test.end());
    	print(Test);
    	merge_sort(Test,0,Test.size() - 1);
    	print(Test);
    	system("pause");
    	return 0;
    }

###Testing