#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#define INF 100002
using namespace std;
struct point {
double x;
double y;
};
point p[100002];
point p1[100002];
point p2[100002];
//point flagp[6];
bool cmpx(point a, point b) {
if (a.x != b.x) {
return a.x < b.x;
}
else {
return a.y < b.y;
}
}
bool cmpy(point a, point b) {
if (a.y != b.y) {
return a.y < b.y;
}
else {
return a.x > b.x;
}
}
double func(int number, int left, int right) {
double len1, len2, minlen, l;
int num1, num2, k = 0;
if (number == 2) {
return sqrt((p[left].x - p[right].x) * (p[left].x - p[right].x) +
(p[left].y - p[right].y) * (p[left].y - p[right].y));
}
else if (number < 2) {
return INF;
}
else {
num1 = number / 2;
num2 = number - num1;
len1 = func(num1, left, left + num1 - 1);
len2 = func(num2, left + num1, right);
minlen = len1 < len2 ? len1 : len2;
l = (p[(left + right - 1) / 2].x + p[(left + right - 1) / 2 + 1].x) / 2;
for (int i = left; i <= (left + right - 1) / 2; i++) {
if (fabs(p[i].x - l) < minlen) {
p1[k].x = p[i].x;
p1[k].y = p[i].y;
k++;
}
}
sort(p1, p1 + k, cmpy);
int k2 = 0;
for (int i = (left + right - 1) / 2 + 1; i <= right; i++) {
if (fabs(l - p[i].x) < minlen) {
p2[k2].x = p[i].x;
p2[k2].y = p[i].y;
k2++;
}
}
sort(p2, p2 + k2, cmpy);
double flaglen = INF;
for (int i = 0; i < k; i++) {
for (int j = 0; j < k2; j++) {
if (p2[j].y - p1[i].y < minlen) {
flaglen = sqrt((p2[j].x - p1[i].x) * (p2
[j].x - p1[i].x) + (p2[j].y - p1[i].y) * (p2[j].y - p1[i].y));
if (flaglen < minlen) {
minlen = flaglen;
}
}
}
}
return minlen;
}
}
int main() {
int num;
cin >> num;
for (int i = 0; i < num; i++) {
cin >> p[i].x >> p[i].y;
}
sort(p, p + num, cmpx);
cout << func(num, 0, num - 1) << endl;
return 0;
}
這篇文章給的思路很清晰!http://blog.csdn.net/zyh15/article/details/49050841