經典排序（待補充~

文章目錄

• • 快排
  • 歸并排序
  • 桶排序

快排

void qsort(int a[],int l,int r){
    if(l == r) return;

    int i = l - 1,j = r + 1,m = a[l + r >> 1];
    while(i < j){
        do i ++;while(a[i] < m);
        do j --;while(a[j] > m);
        if(i < j) swap(a[i],a[j]);
    }

    qsort(a, l, j);
    qsort(a, j + 1, r);
}
           

歸并排序

int a[N],c[N];
void merge_sort(int l,int r){
    if(l >= r) return;
    int mid = l + r >> 1;
    merge_sort(l, mid);
    merge_sort(mid + 1, r);
    int i = l,k = l,j = mid + 1;
    while(i <= mid && j <= r){
        if(a[i] <= a[j]) c[k ++] = a[i ++];
        else c[k ++] = a[j ++];
    }
    while(i <= mid) c[k ++] = a[i ++];
    while(j <= r) c[k ++] = a[j ++];

    for(int m = l;m <= r;m ++) a[m] = c[m];
}
           

桶排序