P3048 [USACO12FEB]牛的IDCow IDs 12通过 67提交 题目提供者lin_toto 标签USACO2012 难度普及/提高- 时空限制1s / 128MB 提交  讨论  题解 最新讨论更多讨论 谁能解释一下这个样例啊.... 题目描述 Being a secret computer geek, Farmer John labels all of his cows with binary numbers. However, he is a bit superstitiou…

题目描述 Being a secret computer geek, Farmer John labels all of his cows with binary numbers. However, he is a bit superstitious, and only labels cows with binary numbers that have exactly K "1" bits (1 <= K <= 10). The leading bit of each la…

题目: FJ给他的奶牛用二进制进行编号,每个编号恰好包含K 个"1" (1 <= K <= 10),且必须是1开头.FJ按升序编号,第一个编号是由K个"1"组成. 请问第N(1 <= N <= 10^7)个编号是什么. 不同寻常的暴力: 样例是升序的第7个,我把1--7都列出来. 1 1 1 1 0 1 1 1 1 0 1 1 1 1 0 1 0 0 1 1 1 0 1 0 1 1 0 1 1 0 发现的规律是,每次将二进制串的从右往左数的第…

题目描述 Being a secret computer geek, Farmer John labels all of his cows with binary numbers. However, he is a bit superstitious, and only labels cows with binary numbers that have exactly K "1" bits (1 <= K <= 10). The leading bit of each la…

传送门 解题思路 组合数学.首先肯定是要先枚举位数,假如枚举到第\(i\)位.我们可以把第一位固定,然后那么后面的随意放\(1\),个数就为\(C_{i-1}^{k-1}\).然后每次枚举时如果方案\(>n\)就说明位数为\(i\),否则就让\(n-C_{i-1}^{k-1}\),然后继续枚举下去.这样的话我们就确定了第一位,后面的位其实和数位\(dp\)里试填法的思路差不多,就是看\(n\)是否大于当前位为\(0\)时后面的方案数,如果大就把这一位设为\(1\),然后减掉方案.算组合数有一个小…

P3045 [USACO12FEB]牛券Cow Coupons 71通过 248提交 题目提供者洛谷OnlineJudge 标签USACO2012云端 难度提高+/省选- 时空限制1s / 128MB 提交  讨论  题解 最新讨论更多讨论 86分求救 题目描述 Farmer John needs new cows! There are N cows for sale (1 <= N <= 50,000), and FJ has to spend no more than his budget…

[USACO12FEB]牛券Cow Coupons(堆,贪心) 题目描述 Farmer John needs new cows! There are N cows for sale (1 <= N <= 50,000), and FJ has to spend no more than his budget of M units of money (1 <= M <= 10^14). Cow i costs P_i money (1 <= P_i <= 10^9), b…

P3045 [USACO12FEB]牛券Cow Coupons 贪心题.先选中 \(c_i\) 最小的 \(k\) 头牛,如果这样就超过 \(m\) ,直接退出,输出答案.否则考虑把后面的牛依次加入,替换前面用过券的牛.这里贪心得选择省钱最少的牛替换掉(这样影响最小,最有可能多买几头).加入牛的顺序按照 \(p\) 从小到大,因为如果换不掉就只能话 \(p\) 的钱去买 #include<bits/stdc++.h> using namespace std; #define int long…

嘟嘟嘟 这其实是一道贪心题,而不是dp. 首先我们贪心的取有优惠券中价值最小的,并把这些东西都放在优先队列里,然后看[k + 1, n]中,有些东西使用了优惠券减的价钱是否比[1, k]中用了优惠券的物品更划算,是的话就更新. #include<cstdio> #include<iostream> #include<cmath> #include<algorithm> #include<cstring> #include<cstdlib&g…

LuoguP3045 [USACO12FEB]牛券Cow Coupons 果然我贪心能力还是太差了 ZR讲过的原题我回来对做法没有一丁点印象 有时候有这样一种题目 每个数有两种不同的价值 你可以选择价值低的,也可能花费一些神秘能力去获得价值高的 这时候我们直接贪心就可能会出现这种情况 当前最后解不是全局最优解 一般这种时候有两节决策, 要么DP 要么尝试进行可反悔的贪心 我们先按照所有牛的优惠后的价格排序,开一个小根堆 将前\(k\)个用优惠劵去买,很明显这可能是错误的 我们就将优惠券买的每一头…