cluster二维数组存放数据的编号，每次计算两个簇的距离，找出距离最近的，将其中一个簇的编号加入另一个编号的一维序列中，再将这个编号清除，之后再循环cluster。

#include<vector>
#include <iostream>
#include <fstream>
#include <sstream>
using namespace std;struct	Point
{double x;double y;
};double distance(const Point& a, const Point& b)
{double x = a.x - b.x;double y = a.y - b.y;return sqrt(x * x + y * y);
}vector<vector<int>> agens(const vector<Point>& data,int k)
{int n = data.size();vector<vector<int>> cluster;for (int i = 0; i < n; i++){cluster.push_back({ i });}while (cluster.size() > k){int index_i = 0;int index_j = 1;double min = distance(data[cluster[0][0]], data[cluster[1][0]]);for (int i = 0; i < cluster.size(); i++)						//找出距离最近的两个簇{for (int j = i + 1; j < cluster.size(); j++){double dis = distance(data[cluster[i][0]], data[cluster[j][0]]);	if (dis < min){index_i = i;index_j = j;min = dis;}}}cluster[index_i].insert(cluster[index_i].end(), cluster[index_j].begin(), cluster[index_j].end());cluster.erase(cluster.begin() + index_j);}return cluster;}vector<Point> ReadData(string filename)
{vector<Point>  data;ifstream file(filename);if (file.is_open()){string line;while (getline(file, line)){istringstream iss(line);double x, y;string token;Point point;if (getline(iss, token, ',') && istringstream(token) >> point.x &&getline(iss, token, ',') && istringstream(token) >> point.y) {data.push_back(point);}/*if (iss >> x >> y){data.push_back({ x, y });}*/}}else{cout << "open fail";}file.close();return data;
}
int main()
{//vector<Point> Data = { {1, 1}, {1, 2}, {2, 1}, {2,2}, {3, 4},{3,5} ,{4,4} ,{4,5} };vector<Point> Data = ReadData("data2.txt");int k;cin >> k;vector<vector<int>> labels;labels=agens(Data, k);for (const vector<int>& row : labels){cout << "{";int size = row.size();for (int i = 0; i < size; i++){cout << row[i] + 1;if (i != size - 1){cout << ",";}}cout << "}";}}

关键在于理解 distance(data[cluster[i][0]], data[cluster[j][0]]);

结果：

数据1：注释部分

数据2：data2.txt