1.单链表

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int N = 1000010;

int h,e[N],ne[N],idx;
int m;

void addhead(int x){
	e[idx] = x;
	ne[idx] = h;
	h = idx ++;
}

void add(int k,int x){
	e[idx] = x;
	ne[idx] = ne[k];
	ne[k] = idx ++;
}

void delete1(int k){
	ne[k] = ne[ne[k]];
}

int main()
{
	cin>>m;
	char op[2];
	h = -1;
	while(m--){
		scanf("%s",&op);
		if(op[0] == 'H'){
			int x;
			cin>>x;
			addhead(x);
		}
		if(op[0] == 'I'){
			int k,x;
			cin>>k>>x;
			add(k-1,x);
		}
		if(op[0] == 'D'){
			int k;
			cin>>k;
			if (k == 0) h = ne[h];//删除头节点要特判！！！！ 
			delete1(k-1);
		}
	}	
	
	for(int i=h;i!=-1;i=ne[i]){
		int j = e[i];
		cout<<j<<' ';
	}
	return 0;
}

2.栈：读入string要用cin

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int N = 1000010;

int m;
int st[N];
int tt = -1;

int main()
{
	cin>>m;
	
	while(m--)
	{
		string op;
		cin>>op;
		
		if(op == "push"){
			int x;
			cin>>x;
			st[++tt] = x;
		}
		if(op == "empty"){
			if(tt==-1) cout<<"YES"<<endl;
			else cout<<"NO"<<endl;
		}
		if(op == "query"){
			cout<<st[tt]<<endl;
		}
		if(op == "pop"){
			tt--;
		}
	}
	return 0;
 } 

3.队列

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int N = 1000010;

int m;
int q[N];
int tt = -1,hh;

int main()
{
	cin>>m;
	
	while(m--)
	{
		string op;
		cin>>op;
		
		if(op == "push"){
			int x;
			cin>>x;
			q[++tt] = x;
		}
		if(op == "empty"){
			if(hh>tt) cout<<"YES"<<endl;
			else cout<<"NO"<<endl;
		}
		if(op == "query"){
			cout<<q[hh]<<endl;
		}
		if(op == "pop"){
			hh++;
		}
	}
	return 0;
 } 

4.单调栈

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int N = 1000010;

int n;
int st[N];
int tt;

int main()
{
	cin>>n;
	for(int i=0;i<n;i++){
		int x;
		cin>>x;
		
		while(tt && st[tt] >= x){
			tt--;
		}
		
		if(tt) cout<<st[tt]<<' ';//第一个数序号是0，输出-1 
		else cout<<"-1"<<' ';
		
		st[++tt] = x;
	}
	
	return 0; 
}

5.单调队列：注意第二次更新hh=0,tt=-1

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int N = 1000010; 

int n,k;
int q[N],hh,tt=-1;
int a[N];

int main()
{
	cin>>n>>k;
	for(int i=0;i<n;i++) cin>>a[i];
	 //找最小值 
	for(int i=0;i<n;i++){
		
		while(hh<=tt && i-k+1 > q[hh]){
			hh++;//q数组是下标 
		}
		while(hh<=tt && a[q[tt]] >= a[i]){
			tt--;//则不可能作为答案输出 
		} 
		q[++tt] = i;//要先添加进来，在窗口里，可能作为答案输出 
		if(i >= k-1){
			cout<<a[q[hh]]<<' ';
		}
	}
	cout<<endl;
	//找最大值
	int hh=0,tt=-1;
	for(int i=0;i<n;i++){
		
		while(hh<=tt && i-k+1 > q[hh]){
			hh++;//q数组是下标 
		}
		while(hh<=tt && a[i] >= a[q[tt]]){
			tt--;//则不可能作为答案输出 
		} 
		q[++tt] = i;//要先添加进来，在窗口里，可能作为答案输出 
		if(i >= k-1){
			cout<<a[q[hh]]<<' ';
		}
	} 
	return 0; 
 } 

 6.kmp

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int M = 1000010;  
const int N = 100010; 
int n,m;
char p[N]; 
char s[M];
int ne[N];

int main()
{
	cin>>n>>p+1>>m>>s+1;
	//求ne数组
	for(int i=2,j=0;i<=n;i++){//从2开始求ne数组
		//回退
		while(j && p[i]!=p[j+1]){
			j=ne[j];
		} 
		if(p[i] == p[j+1]) j++;
		ne[i] = j;
	} 
	//比对
	for(int i=1,j=0;i<=m;i++){//从第一个开始比对
		while(j && s[i]!=p[j+1]){
			j=ne[j];
		} 
		if(s[i] == p[j+1]) j++;
		if(j==n){//比对成功
		    cout<<i-n<<' ';
		    j=ne[j];//成功之后要回退！！！！！！！！！
		}
    		
	} 
	return 0;
}

7.trie字典树

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int M = 1000010;  
const int N = 100010; 

int son[N][26],cnt[N],idx;
int n;

void insert(char str[]){
	int p=0;
	for(int i=0;str[i];i++){
		int u=str[i] - '0';
		if(!son[p][u]){
			son[p][u] = ++idx;//不存在就创建 
		}
		p = son[p][u];
	}
	cnt[p]++; 
	return; 
}

int query(char str[]){
	int p=0;
	for(int i=0;str[i];i++){
		int u = str[i]-'0';
		if(!son[p][u]) return 0;
		p=son[p][u];
	}
	return cnt[p];
}

int main()
{
	cin>>n;
	char op[2];

	char a[N];
	while(n--){
			cin>>op;
		if(op[0] == 'I'){

			cin>>a;
			insert(a);
		}
		if(op[0] == 'Q'){
			cin>>a;
			cout<<query(a)<<endl;
		}
	}	
}

8.并查集

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int M = 1000010;  
const int N = 100010; 

int n,m;
int p[N]; 

int find1(int x){
	if(p[x] != x) p[x] = find1(p[x]);
	return p[x];
}


int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		p[i] = i;//最开始自己是自己的父亲 
	}
	char op[2];
	while(m--){
		cin>>op;
		if(op[0] == 'M'){
			int a,b;
			cin>>a>>b;
			if(p[find1(a)] == p[find1(b)]) continue;
			p[find1(a)] = find1(b);
		}
		if(op[0] == 'Q'){
			int a,b;
			cin>>a>>b;
			if(p[find1(a)] == p[find1(b)]) cout<<"Yes"<<endl;
			else cout<<"No"<<endl;
		}
	}
	return 0;
}

9.并查集的连通块

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int M = 1000010;  
const int N = 100010; 

int n,m;
int p[N],size1[N]; 

int find1(int x){
	if(p[x] != x) p[x] = find1(p[x]);
	return p[x];
}


int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		p[i] = i;//最开始自己是自己的父亲 
		size1[i] = 1;
	}
	char op[2];
	while(m--){
		cin>>op;
		if(op[0] == 'C'){
			int a,b;
			cin>>a>>b;
			if(p[find1(a)] == p[find1(b)]) continue;
			size1[find1(b)]+=size1[find1(a)];
			p[find1(a)] = find1(b);			
		}
		else if(op[1] == '1'){
			int a,b;
			cin>>a>>b;
			if(p[find1(a)] == p[find1(b)]) cout<<"Yes"<<endl;
			else cout<<"No"<<endl;
		}
		else{
			int a;
			cin>>a;
			int fa = size1[find1(a)];
			cout<<fa<<endl;
		}
	}
	return 0;
}

10.堆排序数组模拟

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>

using namespace std;
const int M = 1000010;  
const int N = 100010; 

int n,m;
int heap[N],cnt;


void down(int u){
	int t=u;
	if(u*2 <= cnt && heap[u*2] < heap[t]){
		t=u*2;
	}	
	if(u*2+1 <= cnt && heap[u*2+1] < heap[t]){
		t=u*2+1;
	}
	if(t!=u){
		swap(heap[u],heap[t]);
		down(t);
	}
	return;
}
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>heap[i];
	}
	cnt=n;
	for(int i=n/2;i;i--) down(i);
	while(m--){
		cout<<heap[1]<<' ';
		heap[1] = heap[cnt--];
		down(1);
	}
	return 0;
}