Merge Sort （C++ 实现）

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#include <iostream>
using namespace std;

void mergeArray(int a[], int beg, int mid, int end, int tmp[]) {
    int i = beg, j = mid+1;
    int m =  mid, n = end;
    int k = 0;
    
    while(i <= m && j <= n) {
        if(a[i] > a[j])
            tmp[k++] = a[j++];
        else
            tmp[k++] = a[i++];
    }
    
    while(i <= m) tmp[k++] = a[i++];
    while(j <= n) tmp[k++] = a[j++];
    
    for(i = 0; i < k; ++i)
        a[beg+i] = tmp[i];
}

void mergeSort(int a[], int beg, int end, int tmp[]) {
    if(beg < end) {
        int mid = (beg + end) / 2;
        mergeSort(a, beg, mid, tmp);
        mergeSort(a, mid+1, end, tmp);
        mergeArray(a, beg, mid, end, tmp);
    }
}

void printArr(int a[], int n) {
    for(int i = 0; i < n; ++i) {
        cout<<a[i]<<" ";
    }
    cout<<endl;
}

int main() {
    int a[] = {1, 5, 9, 4, 6, -3, -7, 9, 19, 8};
    int tmp[10];
    
    printArr(a, 10);
    mergeSort(a, 0, 9, tmp);
    printArr(a, 10);
    
    return 0;
}

 

 

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