博客

一、冒泡排序



O

(

n

2

)

O(n^2)






O


(



n










2









)

#include<iostream>

using namespace std;

const int N = 100010;
int n;
int nums[N];

int main(){
    
    cin >> n;
    
    for(int i = 0; i < n; i++) cin >> nums[i];
    
    for(int i = 0; i < n - 1; i++)
        for(int j = i + 1; j < n; j++)
            if(nums[i] > nums[j]) swap(nums[i], nums[j]);
    
    for(int i = 0; i < n; i++) cout << nums[i] << ' ';
    return 0;
}

二、快速排序



O

(

n

l

o

g

n

)

O(nlogn)






O


(


n


l


o


g


n


)

#include<iostream>

using namespace std;

const int N = 100010;

int n;
int nums[N];

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


int main(){
    
    cin >> n;
    
    for(int i = 0; i< n; i++) cin >> nums[i];
    
    quick_sort(0,n-1);
    
    for(int i = 0; i< n; i++) cout << nums[i] << ' ';
    return 0;
}

三、归并排序



O

(

n

l

o

g

n

)

O(nlogn)






O


(


n


l


o


g


n


)

#include<iostream>

using namespace std;

const int N = 100010;
int n;
int q[N],tmp[N];

void merge_sort(int q[],int l,int r){
    if(l >= r) return;
    
    int mid = (l+r) >> 1;
    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(i = l,j = 0; i <= r; i++,j++) q[i] = tmp[j];
}

int main(){
    cin >> n;
    for(int i = 0; i < n; i++) cin >> q[i];
    merge_sort(q,0,n-1);
    for(int i = 0; i < n; i++) cout << q[i] << ' ';
    return 0;
}