救救我，81WAon #5#11

大众分治，不知道哪里挂了。
路过的神仙麻烦指教一下，谢谢。

#include <bits/stdc++.h>
#define fq(i,a,b) for (int i = (a); i <= (b); i++)
#define fnq(i,a,b) for (int i = (a); i < (b); i++)
#define nfq(i,a,b) for (int i = (a); i >= (b); i--)
#define nfnq(i,a,b) for (int i = (a); i > (b); i--)
#define fe(u) for (int i = head[u]; i; i = edge[i].nxt)
using namespace std;
#define int long long
inline int rd () {
    int f = 1;
    char ch = getchar ();
    while (!isdigit (ch)) (ch == '-' ? (f = -1) : 0), ch = getchar ();
    int num = 0;
    while (isdigit (ch)) num = num * 10 + ch - '0', ch = getchar ();
    return num * f;
}

//以上是 IO/宏

const int maxn = 200200;
const double inf = 4e9;
int n = rd ();
struct point {
    double x, y;
} p[maxn];
bool cmpx (point a, point b) {return a.x < b.x;}
bool cmpy (point a, point b) {return a.y < b.y;}
double dis (point a, point b) {
    return sqrt ((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}

int pt[maxn], cnt;
double dv (int l, int r) {
    if (r - l + 1 == 1) return inf;
    if (r - l + 1 == 2) {
        if (p[l].y >= p[r].y) swap (p[l], p[r]);
        return dis (p[l], p[r]);
    }
    int mid = (l + r) >> 1;
    double d = min (dv (l, mid), dv (mid + 1, r));
    inplace_merge (p + 1, p + mid + 1, p + r + 1, cmpy);
    cnt = 0;
    int midx = p[mid].x;
    fq (i, l, r) if (fabs (p[i].x - midx) <= d) pt[++cnt] = i;
    int j = 1;
    fnq (i, 1, cnt) {
        while (j <= cnt && p[pt[j]].y <= p[pt[i]].y + d) ++j;
        fnq (m, i + 1, j) d = min (d, dis (p[pt[i]], p[pt[m]]));
    }
    return d;

}
signed main () {
    fq (i, 1, n) cin >>p[i].x>> p[i].y;
    sort (p + 1, p + n + 1, cmpx);
    printf ("%.4lf", dv (1, n));

    return 0;
}