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[二分，spfa chenck] 题目描述Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of the cables required to connect his farm

bzoj3343&&洛谷2810 教主的魔法Description 教主最近学会了一种神奇的魔法，能够使人长高。于是他准备演示给XMYZ信息组每个英雄看。于是N个英雄们又一次聚集在了一起，这次他们排成了一列，被编号为1、2、……、N。 每个人的身高一开始都是不超过1000的正整数。教主的魔法每次可以把闭区间[L, R]（1≤L≤R≤N）内的英雄的身高全部加上一个整数W。（虽然L=R时并不符合区间