Codeforces Round #481 (Div. 3) A. Remove Duplicates

末蓝、 2022-05-18 05:53 143阅读 0赞

题目链接：[http://codeforces.com/contest/978/problem/A][http_codeforces.com_contest_978_problem_A]  
A. Remove Duplicates  
time limit per test1 second  
memory limit per test256 megabytes  
inputstandard input  
outputstandard output  
Petya has an array  
a  
consisting of  
n  
integers. He wants to remove duplicate (equal) elements.

Petya wants to leave only the rightmost entry (occurrence) for each element of the array. The relative order of the remaining unique elements should not be changed.

Input  
The first line contains a single integer  
n  
(  
1  
≤  
n  
≤  
50  
) — the number of elements in Petya’s array.

The following line contains a sequence  
a  
1  
,  
a  
2  
,  
…  
,  
a  
n  
(  
1  
≤  
a  
i  
≤  
1  
000  
) — the Petya’s array.

Output  
In the first line print integer  
x  
— the number of elements which will be left in Petya’s array after he removed the duplicates.

In the second line print  
x  
integers separated with a space — Petya’s array after he removed the duplicates. For each unique element only the rightmost entry should be left.

Examples  
inputCopy  
6  
1 5 5 1 6 1  
outputCopy  
3  
5 6 1  
inputCopy  
5  
2 4 2 4 4  
outputCopy  
2  
2 4  
inputCopy  
5  
6 6 6 6 6  
outputCopy  
1  
6

直接上代码，有注释：

#include<iostream>
    #include<cmath>
    #include<cstring>
    #include<algorithm>
    #include<sstream>
    #include<map>
    #include<set>
    using namespace std;
    set<int> s;
    set<int> s1; 
    map<int,int> m;
    int main(){
        int n;
        cin>>n;
        int *a=new int[n];
        for(int i=0;i<n;i++){
            cin>>a[i];
            s.insert(a[i]);//用set统计不同的数字个数 
            m[a[i]]=i;//更新每个点的下标 ，记录最右边的下标 
        }
    
        printf("%d\n",s.size());
        int first=1;
        for(int i=0;i<n;i++){
    
            if(i==m[a[i]]&&first){
                printf("%d",a[i]);
                first=0;
            }
            else if(i==m[a[i]]){
                printf(" %d",a[i]);
            }
        }
        printf("\n");
        delete a;
        return 0;
    
    }

[http_codeforces.com_contest_978_problem_A]: http://codeforces.com/contest/978/problem/A