【c++图论】洛谷P2872 [USACO07DEC]Building Roads S

题目描述

Farmer John had just acquired several new farms! He wants to connect the farms with roads so that he can travel from any farm to any other farm via a sequence of roads; roads already connect some of the farms.

Each of the N (1 ≤ N ≤ 1,000) farms (conveniently numbered 1..N) is represented by a position (Xi, Yi) on the plane (0 ≤ Xi ≤ 1,000,000; 0 ≤ Yi ≤ 1,000,000). Given the preexisting M roads (1 ≤ M ≤ 1,000) as pairs of connected farms, help Farmer John determine the smallest length of additional roads he must build to connect all his farms.

给定 nn 个点的坐标，第 ii 个点的坐标为 (x_i,y_i)(xi​,yi​)，这 nn 个点编号为 11 到 nn。给定 mm 条边，第 ii 条边连接第 u_iui​ 个点和第 v_ivi​ 个点。现在要求你添加一些边，并且能使得任意一点都可以连通其他所有点。求添加的边的总长度的最小值。

输入格式

* Line 1: Two space-separated integers: N and M

* Lines 2..N+1: Two space-separated integers: Xi and Yi

* Lines N+2..N+M+2: Two space-separated integers: i a