C++ Sets

集合(Set)是一種包含已排序物件的關聯容器

set insert 將x插入到容器當中自動遞增排序並去重

#include <iostream>
#include <cstdio>
#include <set>

using namespace std;

int main(int argc, char const *argv[]) {

    set<int> st;
    //向st中輸入數值
    for(int i:{1,4,5,6,9})
        st.insert(i);
    printf("for(int i:{1,4,5,6,9})st.insert(i):");
    for(auto i:st)
        printf("%d%c",i," \n"[i == 9]);

    //find()返回一個指向被查詢到元素的迭代器
    cout << "set<int>::iterator j = st.find(5):";
    set<int>::iterator j = st.find(5);
    cout << *j << "\n";

    //erase()刪除集合中的元素--刪除元素的迭代器
    set<int>::iterator i;
    cout << "for(i = st.begin();i != st.end();i++)if(*i == 4)st.erase(i):";
    for(i = st.begin();i != st.end();i++)
        if(*i == 4)st.erase(i);
    for(auto i:st)
        printf("%d%c",i," \n"[i == 9]);

    cout << "st.erase(st.find(1)):";
    st.erase(st.find(1));
    for(auto i:st)
        printf("%d%c",i," \n"[i == 9]);

    cout << "st.erase(5):";
    st.erase(5);
    for(auto i:st)
        printf("%d%c",i," \n"[i == 9]);

    //向st中輸入數值
    //原容器中有6和9--set容器會自動去重
    for(int i:{1,4,5,6,9})
        st.insert(i);
    printf("for(int i:{1,4,5,6,9})st.insert(i):");
    for(auto i:st)
        printf("%d%c",i," \n"[i == 9]);
    //向st中插入2
    //set容器會自動遞增排序
    cout << "st.insert(2):";
    st.insert(2);
    for(auto i:st)
        printf("%d%c",i," \n"[i == 9]);

    //刪除2 - 6之前一個元素
    cout << "st.erase(fi,fj):";
    set<int>::iterator fi = st.find(2);
    set<int>::iterator fj = st.find(6);
    st.erase(fi,fj);
    for(auto i:st)
        printf("%d%c",i," \n"[i == 9]);

    //size()集合中元素的數目
    cout << "st.size():";
    cout << st.size() << "\n";

    return 0;
}