文章目录
- pair
- vector
- list
- stack
- queue
- queue
- priority_queue
- queue双端队列
- set
- ✨set集合
- ✨multiset 多重集合
- 了解：unordered_set 无序集合
- map
- 🌟map
- 几乎不用：multimap
- 一般不用：undered_map
pair
- utility
- 示例
#include <iostream>
#include <utility>
using namespace std;
int main() {
pair<int,double> p1(1,3.14);
pair<char,string> p2('a',"hello");
cout<<p1.first<<", "<<p1.second<<endl;
cout<<p2.first<<", "<<p2.second<<endl;
return 0;
}
- 嵌套
- 例如：三维坐标
#include <iostream>
#include <utility>
using namespace std;
int main() {
pair<int,int> p1(1,2);
pair<int,pair<int,int>> p2(3,make_pair(4, 5));
pair<pair<int,int>,pair<int,int>> p3(make_pair(6, 7),make_pair(3, 5));
cout<<p1.first<<", "<<p1.second<<endl;
cout<<p2.first<<", "<<p2.second.first<<", "<<p2.second.second<< endl;
cout<<p3.first.first<<" ,"<<p3.first.second<<" ,"<<p3.second.first<<" ,"<<p3.second.second<<endl;
return 0;
}
- 示例
#include <iostream>
#include <utility>
#include <vector>
using namespace std;
struct Person{
string name;
int age;
};
int main() {
vector<Person> people;
people.push_back({"Alice",25});
people.push_back({"Bob",30});
people.push_back({"Charlie",20});
vector<pair<Person, int>> scores;
scores.push_back({people[0],90});
scores.push_back({people[1],85});
scores.push_back({people[2],95});
for(const auto& pair : scores){
cout<<"Name: "<<pair.first.name<<endl;
cout<<"Age: "<<pair.first.age<<endl;
cout<<"Score: "<<pair.second<<endl;
cout<<endl;
}
return 0;
}
vector
-
一般用 i<size()或者 (int)size()，如果vector 为空，size()-1 会是很大的数
-
push_back()
-
pop_back()
-
insert()
-
erase()
-
empty()
-
resize()
-
begin(),end()
-
clear()
-
sort()
-
unique()
-
排序并去重：vec.erase(unique(vec.begin(),vec.end()),vec.end());
#include <iostream>
#include <vector>
#include <algorithm>
int main() {
std::vector<int> vec = {2,1,3,2,4,1,5,4};
std::sort(vec.begin(),vec.end());
auto last = unique(vec.begin(),vec.end());
vec.erase(last,vec.end());
for(const auto& num:vec){
std::cout<<num<<" ";
}
return 0;
}
list
- 用的很少，如果需要链表一般用数组模拟或手写链表
- 如果需要随机访问，一半用 vector(),deque()
- push_back()
- push_front()
- pop_back()
- pop_front()
- size()
- empty()
- clear()
- front()
- back()
- begin()
- end()
- insert()
- erase()
stack
- push()
- pop()
- top()
- empty()
- size()
- 将数组元素依次入栈，再依次出栈，可以将数组翻转。（一般不会这么做）
queue
queue
以下都是 O(1)
- push(x)
- pop()
- front()
- empty()
- size()
priority_queue
-
push(x)
-
pop()
-
top()
-
empty()
-
size()
-
#include
-
priority_queue(int，vector,compare/greater) //小根堆
struct Compare{
bool operator()(int a,int b){
return a>b;
}
}
queue双端队列
- 不常用
- push_back(x)
- push_front(x)
- pop_back()
- pop_front()
- front()
- back()
- empty()
- size()
- clear()
#include<bits/stdc++.h>
using namespace std;
int main(){
ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
int m;cin>>m;
queue<string> V,N;
while(m--){
string op;cin>>op;
if(op=="IN"){
string name,q;cin>>name>>q;
if(q=="V")V.push(name);
else N.push(name);
}else{
string q;cin>>q;
if(q=="V")V.pop();
else N.pop();
}
}
while (V.size()) {
cout<<V.front()<<'\n';
V.pop();
}
while(N.size()){
cout<<N.front()<<"\n";
N.pop();
}
return 0;
}
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
int main(){
ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
int n;cin>>n;
priority_queue<ll,vector<ll>,greater<ll>> pq;
for(int i=1;i<=n;++i){
ll x;cin>>x;
pq.push(x);
}
ll ans = 0;
while(pq.size()>=2){
ll x = pq.top();pq.pop();
ll y = pq.top();pq.pop();
ans += x+y;
pq.push(x+y);
}
cout<<ans<<"\n";
return 0;
}
set
✨set集合
- 无重复，默认降序
- insert(x)
- erase(x)
- find(x)
#include<iostream>
#include<set>
using namespace std;
int main( ){
set<int,greater<int>> mySet;
mySet.insert(25);
mySet.insert(17);
mySet.insert(39);
mySet.insert(42);
for(const auto& elem:mySet)cout<<elem<<" ";
cout<<endl;
return 0;
}
#include<iostream>
#include<set>
using namespace std;
struct MyCompare{
bool operator()(const int& a,const int& b)const{
return a>b;
}
};
int main( ){
set<int,MyCompare> mySet;
mySet.insert(25);
mySet.insert(17);
mySet.insert(39);
mySet.insert(42);
for(const auto& elem : mySet){
cout<< elem << " ";
}
cout<<endl;
return 0;
}
✨multiset 多重集合
- 允许存储重复元素
- 二分：
- lower_bound:返回第一个不小于给定值的迭代器
- upper_bount:返回第一个不大于给定值的迭代器
- st.erase(st.find(x))
了解：unordered_set 无序集合
- 无重复，无顺序
map
🌟map
- 存储键值对
#include <iostream>
#include <map>
using namespace std;
int main() {
//创建并初始化multimap
multimap<int, string> myMultimap = {{1, "Apple"}, {2, "Banana"}, {3, "Orange"}};
//判断元素是否存在
if (myMultimap.count(2) == 0) {
cout << "Key 2 not found." << endl;
}
//插入元素
myMultimap.insert(make_pair(4, "Grapes"));
//清空multimap
myMultimap.clear();
//判断multimap是否为空
if (myMultimap.empty()) {
cout << "Multimap is empty." << endl;
} else {
//查找和访问元素
auto range = myMultimap.equal_range(3);
for (auto it = range.first; it != range.second; ++it) {
cout << "Key: " << it->first << ", Value: " << it->second << endl;
}
}
//遍历并打印multimap中的元素
for (const auto& pair : myMultimap) {
cout << "Key: " << pair.first << ", Value: " << pair.second << endl;
}
//删除元素
myMultimap.erase(3);
return 0;
}
