# SkyWT

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$$\sum_{i=1}^{n-1} \sum_{j=i+1}^{n} lcm(i,j)$$

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HDU 4045 Machine scheduling：题目链接

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BZOJ原题链接）这题是可以推出公式的：F[i]=F[i-1]*3-F[i-2]+2。套个高精度就好了。（由于需要用到的知识太复杂，推不来……）（其实可以写个暴力推出来）

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POJ题目链接

N soldiers of the land Gridland are randomly scattered around the country.
A position in Gridland is given by a pair (x,y) of integer coordinates. Soldiers can move - in one move, one soldier can go one unit up, down, left or right (hence, he can change either his x or his y coordinate by 1 or -1).

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