素数通道 题目大意:给定两个素数a,b,要你找到一种变换,使得每次变换都是素数,如果能从a变换到b,则输出最小步数,否则输出Impossible 水题,因为要求最小步数,所以我们只需要找到到每个素数的最小步数就可以了,每个权都是1,所以用BFS就可以了,一开始我还用DFS,太丢人了,一开始就把素数表打好就可以了 #include <iostream> #include <functional> #include <algorithm> using namespace s…

Prime Path(POJ - 3126) 题目链接 算法 BFS+筛素数打表 1.题目主要就是给定你两个四位数的质数a,b,让你计算从a变到b共最小需要多少步.要求每次只能变1位,并且变1位后仍然为质数. 2.四位数的范围是1000~9999,之间共有1000多个质数.由于已经知道位数为4位,所以可以通过BFS来寻找最小步数.每次需要分别变换个位.十位.百位.千位,并且把符合要求的数放到队列中,同时需标记这个数已经遍历过一次,避免重复遍历,直到找到目标数. C++代码 #include<io…

题目链接:https://vjudge.net/problem/POJ-3126 题意:给你两个四位的素数N,M,每次改变N四位数中的其中一位,如果能经过有限次数的替换变成四位数M,那么求出最少替换次数,否则输出“Impossible”.(N,M必须一直是素数) 思路:bfs.四位数,每一位可以替换为0~9,那么我们可以每次改变N中的一位数,然后放入队列中,当然,在替换数字时难免会出现重复的四位数,这样会造成TLE,那么我们可以创建一个bool数组标记出现过的,我们也需要素数筛999 ~ 100…

Prime Path POJ - 3126 题意: 给出两个四位素数 a , b.然后从a开始,每次可以改变四位中的一位数字,变成 c,c 可以接着变,直到变成b为止.要求 c 必须是素数.求变换次数的最小值.(a,b,c都是四位数字,输入时没有前导零) 分析: 每次改变可以获得一个四位数c,然后如果c是素数并且之前没有出现过,那么我们把它放入队列即可. int f[10001]; int v[10001]; void init()//素数筛 { memset(f,0,sizeof f); fo…

  POJ 3126  Prime Path Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 16204   Accepted: 9153 Description The ministers of the cabinet were quite upset by the message from the Chief of Security stating that they would all have to change…

题目链接:http://poj.org/problem?id=3126 Prime Path Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 32036   Accepted: 17373 Description The ministers of the cabinet were quite upset by the message from the Chief of Security stating that they…

POJ 3126 Prime Path(素数路径) Time Limit: 1000MS    Memory Limit: 65536K Description - 题目描述 The ministers of the cabinet were quite upset by the message from the Chief of Security stating that they would all have to change the four-digit room numbers on…

题目传送门 /* 题意:从一个数到另外一个数,每次改变一个数字,且每次是素数 BFS:先预处理1000到9999的素数,简单BFS一下.我没输出Impossible都AC,数据有点弱 */ /************************************************ Author :Running_Time Created Time :2015-8-2 15:46:57 File Name :POJ_3126.cpp ****************************…

Description The ministers of the cabinet were quite upset by the message from the Chief of Security stating that they would all have to change the four-digit room numbers on their offices.  — It is a matter of security to change such things every now…

Prime Path Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 15325   Accepted: 8634 Description The ministers of the cabinet were quite upset by the message from the Chief of Security stating that they would all have to change the four-dig…