破圈法求图的最小生成树，破圈法是“见圈破圈”，即如果看到图中有一个圈，就将这个圈的边去掉一条，直至图中再无一圈为止。（其中破圈法的" 圈"指的是回路） -Seek the minimal spanning tree to break the circle method, breaking the circle method is to see the ring to break the circle ", that is, if you see a circle in the figure, will circle the edge remove a figure so far is no longer a circle. (Broken circle law "circle" refers to the circuit