90分还能优化吗

#include <bits/stdc++.h>
using namespace std;
int n;
double x[20], y[20];
bool vis[20];
double ans = 1e9;
void dfs(double xa, double xb, int count, double sum) {
    if (sum >= ans) return;
    if (count == n) {
        ans = sum;
        return;
    }
    for (int i = 1; i <= n; i++) {
        if (!vis[i]) {
            vis[i] = true;
            double dist = sqrt((xa - x[i]) * (xa - x[i]) + (xb - y[i]) * (xb - y[i]));
            dfs(x[i], y[i], count + 1, sum + dist);
            vis[i] = false;
        }
    }
}

int main() {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        scanf("%lf%lf", &x[i], &y[i]);
    }
    
    dfs(0.0, 0.0, 0, 0.0);
    printf("%.2f", ans);
    return 0;
}