1.选择排序
void sort(int a[], int l, int r){
    for(int i= l; i<=r; i++){
        for(int j=i+1; j<=r; j++){
            if(a[i]>a[j]) swap(a[i],a[j]);
        }
    }
}

2.快速排序
void quick_sort(int q[],int l,int r) {
    if (l >= r) return;
    int i = l - 1;
    int j = r + 1;
    int x = q[(l + r) / 2];
    while (i < j) {
        do i++ ; while (q[i] < x);
        do j-- ; while (q[j] > x);
        if (i < j) swap(q[i], q[j]);
    }
    quick_sort(q, l, j), quick_sort(q, j + 1, r);
}

3.归并排序
void merge_sort(int q[], int l, int r){
    if(l>=r) return;
    int mid= (l + r )/2;
    merge_sort(q,l,mid),merge_sort(q,mid+ 1,r);
    int k=0,i=l,j=mid+ 1;
    while(i<=mid && j<=r) {
        if (q[i]<=q[j]) tmp[k++]=q[i++];
        else tmp[k++]=q[j++];
    }
    while(i<=mid) tmp[k++]=q[i++];
    while(j<=r) tmp[k++]=q[j++];

    for ( k = 0, i=l;i<=r;k++,i++ ) q[i]=tmp[k];
    //for (  i=l,j=0;i<=r;i++,j++ ) q[i]=tmp[j];
 }