bfs. /* 2717 */ #include <iostream> #include <cstdio> #include <cstring> #include <cstdlib> #include <queue> using namespace std; #define MAXN 100001 queue<int> Q; int s[MAXN]; int n, k; int ans; void bfs() { int cur, n…

看题:http://acm.hdu.edu.cn/showproblem.php?pid=2717 思路:相当于每次有三个方向,加1,减1,乘2,要注意边界条件,减1不能小于0,乘2不能超过最大值. 然后还要注意N>=K的时候,只能减1才能到达. #include <iostream> #include <string> #include <cstdio> #include <cmath> #include <vector> #includ…

简单BFS.就是要把所有的D点当成一个整体考虑(整体移动). /* 2531 */ #include <iostream> #include <queue> #include <cstdio> #include <cstring> #include <cstdlib> using namespace std; #define MAXN 105 typedef struct { ], y[]; int t; } node_t; int dn, n,…

#include<stdio.h> #include<string.h> struct A{ int state; int step; }queue[]; // 结构体数组用来模拟队列,数组元素包含两个数据,state代表遍历到的数值,step所经历的步数 ]; // 这个数组用来存储访问情况 int n, k; int bfs( int aim); int main(void){ scanf("%d%d", &n, &k); if( n >…

题目链接:http://poj.org/problem?id=3278 题意:有一头奶牛跑到了K的位置,农夫在N的位置,求最短抓到奶牛的时间. 农夫有两种移动方式. 1.步行:一分钟内从x->x+1 或者 x->x-1. 2.传送:一分钟内从x->2x. 题解:一个BFS例题.基础练手用的.queue里其实有三种状态.x-1,x+1,2x.然后去试探鸭. 代码: #include<iostream> #include<queue> #include<cstr…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=2717 Catch That Cow Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 12615    Accepted Submission(s): 3902 Problem Description Farmer John has been…

HDU 2717 题目大意:在x坐标上,农夫在n,牛在k.农夫每次可以移动到n-1, n+1, n*2的点.求最少到达k的步数. 思路:从起点开始,分别按x-1,x+1,2*x三个方向进行BFS,最先找到的一定是最小的步数. /* HDU 2717 Catch That Cow --- BFS */ #include <cstdio> #include <cstring> #include <queue> using namespace std; ]; int n, k…

传送门:http://acm.hdu.edu.cn/showproblem.php?pid=2717 Catch That Cow Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 20259    Accepted Submission(s): 5926 Problem Description Farmer John has been i…

Catch That Cow Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 9276    Accepted Submission(s): 2907 Problem Description Farmer John has been informed of the location of a fugitive cow and wants…

Catch That Cow Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number line. Farmer…

Catch That Cow Time Limit: 5000/2000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 12798 Accepted Submission(s): 3950 Problem Description Farmer John has been informed of the location of a fugitive cow and wants to c…

Catch That Cow Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 6383    Accepted Submission(s): 2034 Problem Description Farmer John has been informed of the location of a fugitive cow and wants…

[算法]数学置换 [题意]给定n个数,要求通过若干次交换两个数的操作得到排序后的状态,每次交换代价为两数之和,求最小代价. [题解] 考虑置换的定义:置换就是把n个数做一个全排列. 从原数组到排序数组的映射就是经典的置换,这样的置换一定能分解成循环的乘积. 为什么任意置换都可以这样分解:原数组的每个数要交换到排序位置(有后继),每个数的原位置会有数字来替代(有前驱),故一定构成若干循环节. 循环节内要完成置换,需要按顺序依次替换位置进行len-1次对换(len为循环节长度). 对于每一循环节内部…

题目链接:http://i.cnblogs.com/EditPosts.aspx?opt=1 Catch That Cow Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 7909    Accepted Submission(s): 2498 Problem Description Farmer John has been inform…

[算法]并查集+平衡树+数学+扫描线 [题解] 经典曼哈顿距离转切比雪夫距离. 曼哈顿距离:S=|x1-x2|+|y1-y2|<=c 即:max(x1-x2+y1-y2,x1-x2-y1+y2,-x1+x2+y1-y2,-x1+x2-y1+y2) 令X1=x1+y1,Y1=x1-y1,则转化为 切比雪夫距离:S=max(|X1-X2|,|Y1-Y2|)<=c. 为什么要转化为切比雪夫距离?因为这种形式很容易操作. 想象两者的几何意义,哈夫曼距离<=c是竖着的正方形,而切比雪夫距离<…

Catch That Cow Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 8999    Accepted Submission(s): 2837 Problem Description Farmer John has been informed of the location of a fugitive cow and wants…

Problem Description Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number line. F…

Problem Description Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number line. F…

其实是求树上的路径间的数据第K大的题目.果断主席树 + LCA.初始流量是这条路径上的最小值.若a<=b,显然直接为s->t建立pipe可以使流量最优:否则,对[0, 10**4]二分得到boundry,使得boundry * n_edge - sum_edge <= k/b, 或者建立s->t,然后不断extend s->t. /* 4729 */ #include <iostream> #include <sstream> #include <…

题目链接 Problem Description Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number li…

Problem Description Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number line. F…

Description The N (2 <= N <= 10,000) cows are so excited: it's prom night! They are dressed in their finest gowns, complete with corsages and new shoes. They know that tonight they will each try to perform the Round Dance. Only cows can perform the…

DP/四边形不等式 裸题环形石子合并…… 拆环为链即可 //HDOJ 3506 #include<cmath> #include<vector> #include<cstdio> #include<cstring> #include<cstdlib> #include<iostream> #include<algorithm> #define rep(i,n) for(int i=0;i<n;++i) #define…

DP/四边形不等式 这题跟石子合并有点像…… dp[i][j]为将第 i 个点开始的 j 个点合并的最小代价. 易知有 dp[i][j]=min{dp[i][j] , dp[i][k-i+1]+dp[k+1][j-(k-i+1)]+w(i,k,j)} (这个地方一开始写错了……) 即,将一棵树从k处断开成(i,k)和(k+1,i+j-1)两棵树,再加上将两棵树连起来的两条树枝的长度w(i,k,j) 其中,$ w(i,k,j)=x[k+1]-x[i]+y[k]-y[i+j-1] $ 那么根据四边形…

DP/四边形不等式 要求将一个可重集S分成M个子集,求子集的极差的平方和最小是多少…… 首先我们先将这N个数排序,容易想到每个自己都对应着这个有序数组中的一段……而不会是互相穿插着= =因为交换一下明显可以减小极差 然后……直接四边形不等式上吧……这应该不用证明了吧? MLE了一次:这次的w函数不能再开数组去存了……会爆的,直接算就行了= =反正是知道下标直接就能乘出来. 数据比较弱,我没开long long保存中间结果居然也没爆……(只保证最后结果不会爆int,没说DP过程中不会……) //H…

DP/四边形不等式 做过POJ 1739 邮局那道题后就很容易写出动规方程: dp[i][j]=min{dp[i-1][k]+w[k+1][j]}(表示前 j 个点分成 i 块的最小代价) $w(l,r)=\sum_{i=l}^{r}\sum_{j=i+1}^{r}a[i]*a[j]$ 那么就有 $w(l,r+1)=w(l,r)+a[j]*\sum\limits_{i=l}^{r}a[i]$ 所以:w[i][j]明显满足 关于区间包含的单调性 然后我们大胆猜想,小(bu)心(yong)证明,w[…

DP/单调队列优化 呃……环形链求最大k子段和. 首先拆环为链求前缀和…… 然后单调队列吧<_<,裸题没啥好说的…… WA:为毛手写队列就会挂,必须用STL的deque?(写挂自己弱……sigh) //HDOJ 3415 #include<queue> #include<cmath> #include<vector> #include<cstdio> #include<cstring> #include<cstdlib>…

DP/单调队列优化 题解:http://www.cnblogs.com/yymore/archive/2011/06/22/2087553.html 引用: 首先我们要明确几件事情 1.假设我们现在知道序列(i,j)是符合标准的,那么如果第j+1个元素不比(i,j)最大值大也不比最小值小,那么(i,j+1)也是合法的 2.如果(i,j)不合法的原因是差值比要求小,那在(i,j)范围内的改动是无效的,需要加入j+1元素充当最大值或者最小值才可能获得合法的序列 3.假设序列(i,j)的差值比要求大,…

Manacher算法 Manacher模板题…… //HDOJ 3068 #include<cstdio> #include<cstring> #include<cstdlib> #include<iostream> #include<algorithm> #define rep(i,n) for(int i=0;i<n;++i) #define F(i,j,n) for(int i=j;i<=n;++i) #define D(i,j…

数据结构/可并堆 啊……换换脑子就看了看数据结构……看了一下左偏树和斜堆,鉴于左偏树不像斜堆可能退化就写了个左偏树. 左偏树介绍:http://www.cnblogs.com/crazyac/articles/1970176.html 体会:合并操作是可并堆的核心操作(就像LCT里的access),进堆和弹堆顶都是直接调用合并操作实现的. 而合并的实现是一个递归的过程:将小堆与大堆的右儿子合并(这里的大小指的是堆顶元素的大小),直到某个为0.(是不是有点启发式合并的感觉……) 在合并的过程中要维…