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并查集是我暑假从高手那里学到的一招，觉得真是太精妙的设计了。以前我无法解决的一类问题竟然可以用如此简单高效的方法搞定。 来看一个实例，杭电1232畅通工程 首先在地图上给你若干个城镇，这些城镇都可以看作点，然后告诉你哪些对城镇之间是有道路直接相连的。最后要解决的是整幅图的连通性问题。比如随意给你两个点，让你判断它们是否连通，或者问你整幅图一共有几个连通分支，也就是被分成了几个互相独立的块。像畅...

  Now and then you play the following game with your friend. Your friend writes down a sequence consisting of zeroes and ones. You choose a continuous subsequence (for example the subsequence from th...

An earthquake takes place in Southeast Asia. The ACM (Asia Cooperated Medical team) have set up a wireless network with the lap computers, but an unexpected aftershock attacked, all computers in the n...

Given N nodes, each node is labeled with an integer between 1 and 106 (inclusive and labels are not necessarily distinct). Two nodes have an edge between them, if and only if the GCD (Greatest Common ...