1 const int maxn=32790; 2 int euler[maxn+2]; 3 void make() 4 { 5 euler[1]=0; 6 for(int i=2;i<=maxn;++i) 7 euler[i]=i; 8 for(int i...
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其他好文 时间：
2015-07-25 09:24:27
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107
Each of the six faces on a cube has a different digit (0 to 9) written on it; the same is done to a second cube. By placing the two cubes side-by-side in different positions we can
form a variety of...
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其他好文 时间：
2015-07-24 22:42:52
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231
For a number written in Roman numerals to be considered valid there are basic rules which must be followed. Even though the rules allow some numbers to be expressed in more than
one way there is alw...
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其他好文 时间：
2015-07-24 22:42:34
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290
For a number written in Roman numerals to be considered valid there are basic rules which must be followed. Even though the rules allow some numbers to be expressed in more than
one way there is alw...
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其他好文 时间：
2015-07-24 18:29:36
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128
A natural number, N, that can be written as the sum and product of a given set of at least two natural numbers, {a1, a2, ... , ak}
is called a product-sum number: N = a1 + a2 + ... + ak = a1 × a2 × ...
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其他好文 时间：
2015-07-23 23:48:41
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140
The smallest number expressible as the sum of a prime square, prime cube, and prime fourth power is 28. In fact, there are exactly four numbers below fifty that can be expressed
in such a way:
28...
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其他好文 时间：
2015-07-23 21:50:50
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210
In the game, Monopoly, the standard board is set up in the following way:
GO
A1
CC1
A2
T1
R1
B1
CH1
B2
B3
JAIL
H2
C1
T2
U1
H1
C2
CH3
C3
R4
...
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其他好文 时间：
2015-07-22 16:29:45
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94
The minimal path sum in the 5 by 5 matrix below, by starting in any cell in the left column and finishing in any cell in the right column, and only moving up, down, and right, is
indicated in red an...
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其他好文 时间：
2015-07-21 17:10:05
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145
先介绍欧拉函数及其相关定理吧：1.欧拉函数：对于任意一个数X，将其分解质因数为X=(P1^b1)*(P2^b2)*(P3^b3)......则小于X的与X互质的数的个数N为N = X * (1 - 1 / p1) * (1 - 1 / p2).......显然对于质数p,Euler(p) = p -...
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其他好文 时间：
2015-07-21 01:01:12
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188
A common security method used for online banking is to ask the user for three random characters from a passcode. For example, if the passcode was 531278, they may ask for the 2nd,
3rd, and 5th chara...
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其他好文 时间：
2015-07-20 16:47:38
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118
