c_cpp 找到整数数组中的第一个重复元素

Posted 2021-05-14

// https://www.geeksforgeeks.org/find-first-repeating-element-array-integers/
#include <iostream>
#include <set>
using namespace std;

int repeat (int a[], int n) {
    int min = -1;
    set <int> s;

    for (int i=n-1;i>=0;i--){
        if (s.find(a[i]) != s.end())
            min = i;
        else
            s.insert(a[i]);
    }
    return min;
}

int main(){
    int n;
    cin>>n;
    int a[n];
    for (int i=0;i<n;i++)
        cin>>a[i];

    int j= repeat(a,n);
    if (j != -1)
        cout << "Repeating element is: " << a[j];
    else
        cout << "There is no repeating element.";
}