学步园

#include<algorithm>
#include<iostream>
#include<cstdio>
using namespace std;

inline int read() {
    int x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-')f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = x * 10 + ch - '0';
        ch = getchar();
    }
    return x*f;
}

struct edge {
    int x, y, v;
} e[500001];
int n, m, tot, cnt, mx, ans, fa[1001], a[501], x[1001], y[1001];

inline bool cmp(edge a, edge b) {
    return a.v < b.v;
}

inline int find(int x) {
    return x == fa[x] ? x : fa[x] = find(fa[x]);
}

int main() {
    m = read();
    for (int i = 1; i <= m; i++)
        a[i] = read();
    n = read();
    for (int i = 1; i <= n; i++) {
        fa[i] = i;
        x[i] = read();
        y[i] = read();
    }
    for (int i = 1; i < n; i++)
        for (int j = i + 1; j <= n; j++)
            e[++cnt] = (edge){i, j, (x[i] - x[j])*(x[i] - x[j])+(y[i] - y[j])*(y[i] - y[j])};
    sort(e + 1, e + cnt + 1, cmp);
    for (int i = 1; i <= cnt; i++) {
        int p = find(e[i].x), q = find(e[i].y);
        if (p != q) {
            fa[p] = q;
            tot++;
            if (tot == n - 1) {
                mx = e[i].v;
                break;
            }
        }
    }
    for (int i = 1; i <= m; i++)
        if (a[i] * a[i] >= mx)
            ans++;
    printf("%d", ans);
    return 0;
}