算法-数对的使用

1、数对可用于数组排序中，并且可记忆化排序前的元素下标

#include
#include
#include
using namespace std;
typedef long long ll;
const int N = 2e5 + 10;
pair a[N];
void solve() {
    ll n;
    cin >> n;
    for (ll i = 1; i <= n; i++) {
        cin >> a[i].first;
        a[i].second = i;
    }
    sort(a + 1, a + 1 + n);
    cout << "元素:";
    for (ll i = 1; i <= n; i++) {
        cout << a[i].first << " ";
    }
    cout << endl;
    cout << "下标:";
    for (ll i = 1; i <= n; i++) {
        cout << a[i].second << " ";
    }
    cout << endl;
}
int main() {
    std::ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    ll t=1;
    //cin >> t;
    while (t--) {
        solve();
    }
}

 2、例题

#include
#include
#include
using namespace std;
const int N = 2e5 + 10;
pair a[N];
int main(){
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++){
        cin >> a[i].first;
        a[i].second = i;
    }
    sort(a + 1, a + 1 + n);
    for (int i = 2; i <= n; i++){
        if (a[i].first == a[i - 1].first){
            cout << "NO";
            return 0;
        }
    }
    cout << "YES" << '\n';
    for (int i = 1; i <= n; i++){
        cout << a[i].second << " ";
    }
    return 0;
}