order to find its combined meaning, investigate the expression (31) in the \ (c (m,k) \). It is obviously the absolute value of \ (s (m,k) \), and the satisfying formula (32). Easy to verify, containing \ (k\) a rotation of the \ (m\) Yuan permutation number, also satisfies the formula (32) recursion relation, this is its combination meaning.\[s (m,k) =s (m-1,k-1)-(m-1) s (m-1,k) \tag{29}\]\[s (k+r,k) = ( -1) ^r\sum_{1\leqslant k_1\leqslant k_2\leqslant\cdots\leqslant k_r\leqslant k+r}k_1k_2\cd

101 101 197 200 200 200 200413 1133 503 503 503 502 502 417 402 412196 512 186 1 04 87 93 97 97 142 196398 1375 398 398 405 499 499 495 488 471294 1256 296 296 296 296 287 286 286 247Test instructionsCount the number of 0-9 in each position from a to B.Analysis:From this problem more embodies the charm of mathematics ...Either way, find an F (n), count from 1 to N, and then F (b)-F (A-1) results.Recursion is the establishment of the F (k) and F (10*k+x) relationship, that is, for a large number

11401-triangle countingtime limit:1.000 secondsTest instructions: give you n a line, length 1-n. Ask how many different triangles can be formed.Problem Solving Ideas:The triangles with the largest edge length x have C (x), the other two sides are Y and Z respectively, and have y+z>x according to the triangular inequalities. So Z's range is x-y ① According to this inequality, when Y=1 x-1 The ② above contains the Y=z case, and each triangle is two times. So we should count the y=z of the situatio

second largest city, C is the province's third largest cityCity, and so forth. Then there is the post five, and this latter five is the rule, if you are the first one in the province toThe first license plate in the area, theoretically, five digits after your license plate is 00001, if you are the No. 8965 owner, your carThe first five bits of the card should theoretically be 08965, if the license plate exceeds the number of the capacity is the 1 billionth place, fromThe first bit begins with t

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