题意:算出区间内二进制中0的个数大于等于1的个数的数字有多少个 /* 本来以为用数位DP搞,但是组合数更简单. 我们设n的二进制长度为len. ①:先考虑长度小于len的数字. 这里以数字22为例,二进制拆成10110,len=5. len=1时,只能是1(题目要求是正数): len=2时,第一位是1,剩下的1位,至少有1个0,ans+=C(1,1); -- len=k时,第一位是1,剩下的len-k位,如果至少要有p个0,那么ans+=C(len-k,p)+...+C(len-k,len-k)…

Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 7558   Accepted: 2596 Description The cows, as you know, have no fingers or thumbs and thus are unable to play Scissors, Paper, Stone' (also known as 'Rock, Paper, Scissors', 'Ro, Sham, Bo'…

题目传送门 Round Numbers Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 16439   Accepted: 6776 Description The cows, as you know, have no fingers or thumbs and thus are unable to play Scissors, Paper, Stone' (also known as 'Rock, Paper, Scis…

题意:给定区间[l,r],l < r ,求区间中满足条件的正整数的个数:二进制表示下0的个数不少于1的个数. 分析:f(x)表示<=x时满足条件的数的个数,所求问题即为f(r)-f(l-1).x二进制表示下从高到低位为1,bi,bi-1, bi-2, b0, 长度为len, 那么f(x)可以这样求解: dp[i][j]表示从i~0位可以任意为0或1时,0的个数比1多j个情况,由于j可能为负数,所以这里方便处理,将j = 40表示0的个数和1的个数一样多. 转移:dp[i][j] = sum{d…

Fence Repair 问题大意:农夫约翰为了修理栅栏,要将一块很长的木块切割成N块,准备切成的木板的长度为L1,L2...LN,未切割前的木板的长度恰好为切割后木板的长度的总和,每次切断木板的时候,需要的开销为这块木板的长度,例如长度为21的木板需要切成长度为5,8,8的三块木板,长为21的木板切成长为13和8的板时,开销为21,.再将长度为13的板切成长度为5和8的板时,开销是13,于是合计开销是34,然后要你求切割完的最小开销是什么. 乍眼看这一道题好像有很多种切割方案,似乎是很难解决的…

1120 Friend Numbers (20 分) Two integers are called "friend numbers" if they share the same sum of their digits, and the sum is their "friend ID". For example, 123 and 51 are friend numbers since 1+2+3 = 5+1 = 6, and 6 is their friend I…

1100 Mars Numbers(20 分) People on Mars count their numbers with base 13: Zero on Earth is called "tret" on Mars. The numbers 1 to 12 on Earch is called "jan, feb, mar, apr, may, jun, jly, aug, sep, oct, nov, dec" on Mars, respectively.…

1069 The Black Hole of Numbers(20 分) For any 4-digit integer except the ones with all the digits being the same, if we sort the digits in non-increasing order first, and then in non-decreasing order, a new number can be obtained by taking the second…

1023 Have Fun with Numbers(20 分) Notice that the number 123456789 is a 9-digit number consisting exactly the numbers from 1 to 9, with no duplication. Double it we will obtain 246913578, which happens to be another 9-digit number consisting exactly t…

1120 Friend Numbers(20 分) Two integers are called "friend numbers" if they share the same sum of their digits, and the sum is their "friend ID". For example, 123 and 51 are friend numbers since 1+2+3 = 5+1 = 6, and 6 is their friend ID…