HDU 4783 Clumsy Algorithm

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HDU 4783 Clumsy Algorithm

题意不提. 我们可以发现,可以将最终序列分为对于第i个位置i-pi>=0与i-pi<0种两个子序列.且如果f[n]==g[n],则有两个子序列都递增. 原因是f[n]表示1-n这个排列的逆序对个数,即冒泡排序的交换次数,而每个g[i]表示将p[i]从i位置移到它应当在的p[i]位置的交换次数. 考虑将每个满足i-p[i]>0的p[i]从i位置移到p[i]位置是正确的条件,显然对于i-p[i]>0的每个p[i]必须递增,否则,会产生p[i]与p[j]交换时的交叉,使冒泡的代价增大.…

hdu 1052 (greedy algorithm) 分类： hdoj 2015-06-18 16:49 35人阅读评论(0) 收藏

thanks to http://acm.hdu.edu.cn/discuss/problem/post/reply.php?action=support&postid=19638&messageid=1&deep=0 for the test case provided. below is an excerpt data 8 11 9 8 8 8 4 3 2 11 8 8 8 8 4 3 2 answer 800 #include <cstdio> #include…

hdu 3221 Brute-force Algorithm(高速幂取模，矩阵高速幂求fib)

http://acm.hdu.edu.cn/showproblem.php?pid=3221 一晚上搞出来这么一道题..Mark. 给出这么一个程序.问funny函数调用了多少次. 我们定义数组为所求:f[1] = a,f[2] = b, f[3] = f[2]*f[3]......f[n] = f[n-1]*f[n-2].相应的值表示也可为a^1*b^0%p.a^0*b^1%p,a^1*b^1%p,.....a^fib[n-3]*b^fib[n-2]%p.即a,b的指数从n=3以后与fib数列…

hdu 1051 (greedy algorithm, how a little modification turn 15ms to 0ms) 分类： hdoj 2015-06-18 12:54 29人阅读评论(0) 收藏

the 2 version are essentially the same, except version 2 search from the larger end, which reduce the search time in extreme condition from linear to constant, so be faster. version 1 #include <cstdio> #include <algorithm> struct LWPair{ int l…

SPOJ 5152 Brute-force Algorithm EXTREME && HDU 3221 Brute-force Algorithm 快速幂,快速求斐波那契数列,欧拉函数,同余难度:1

5152. Brute-force Algorithm EXTREME Problem code: BFALG Please click here to download a PDF version of the contest problems. The problem is problem B in the PDF. But the data limits is slightly modified: 1≤P≤1000000 in the original description, but i…

HDU 3221 Brute-force Algorithm

题意:问funny被调用了多少次,结果ModP,P不一定为质数. 首先很容易发现递推公式fn=fn-1*fn-2;写出前几项a,b,a*b,a*b^2,a^2*b^3,a^3*b^5;易发现a,b的指数为斐波那契数列.但是当N大一点时,斐波那契数列便变得非常大.那么此时得用欧拉定理降幂. 特别要主要使用条件,x>phi(c). 接着用矩阵快速幂求斐波那契数列,再快速幂求答案即可. #include<cstdio> #include<cstring>…

hdu 1053 (huffman coding, greedy algorithm, std::partition, std::priority_queue ) 分类： hdoj 2015-06-18 19:11 22人阅读评论(0) 收藏

huffman coding, greedy algorithm. std::priority_queue, std::partition, when i use the three commented lines, excution time increase to 15ms from 0ms, due to worse locality? thanks to http://acm.hdu.edu.cn/discuss/problem/post/reply.php?action=support…