Description A Sudoku grid is a 16x16 grid of cells grouped in sixteen 4x4 squares, where some cells are filled with letters from A to P (the first 16 capital letters of the English alphabet), as shown in figure 1a. The game is to fill all the empty g…

[题目链接] http://poj.org/problem?id=3076 [算法] 将数独问题转化为精确覆盖问题,用Dancing Links求解 [代码] #include <algorithm> #include <bitset> #include <cctype> #include <cerrno> #include <clocale> #include <cmath> #include <complex> #in…

DLX精确覆盖模具称号..... Sudoku Time Limit: 10000MS   Memory Limit: 65536K Total Submissions: 4416   Accepted: 2143 Description A Sudoku grid is a 16x16 grid of cells grouped in sixteen 4x4 squares, where some cells are filled with letters from A to P (the f…

3076 思路: dfs + 剪枝 首先,如果这个位置只能填一种字母,那就直接填 其次,如果对于每一种字母,如果某一列或者某一行或者某一块只能填它,那就填它 然后,对于某个位置如果不能填字母了,或者某种字母在一行一列或一块中出向了两次以上,说明当前方案不成立 最后贪心地从可选情况少的往下搜 代码: #pragma GCC optimize(2) #pragma GCC optimize(3) #pragma GCC optimize(4) #include<iostream> #include…

Description A Sudoku grid is a 16x16 grid of cells grouped in sixteen 4x4 squares, where some cells are filled with letters from A to P (the first 16 capital letters of the English alphabet), as shown in figure 1a. The game is to fill all the empty g…

题目大意: 16*16的数独. 思路分析: 多说无益. 想说的就是dancing links 的行是依照 第一行第一列填 1 第一行第二列填 2 -- 第一行第十五列填15 第一行第二列填 1 -- 第二行.... 列的纺织则是 第一行放1,第一行放2,..第十六行放16...第一列放1..第一列放2...第十六列放16..第一块区域放1 ....然后在最后81位就是放自己的位置,准确的说就是 r*m+c. #include <cstdio> #include <iostream>…

Sudoku Time Limit: 10000MS   Memory Limit: 65536K Total Submissions: 5769   Accepted: 2684 Description A Sudoku grid is a 16x16 grid of cells grouped in sixteen 4x4 squares, where some cells are filled with letters from A to P (the first 16 capital l…

Description A Sudoku grid is a 16x16 grid of cells grouped in sixteen 4x4 squares, where some cells are filled with letters from A to P (the first 16 capital letters of the English alphabet), as shown in figure 1a. The game is to fill all the empty g…

和3074仅仅有数目的不同,3074是9×9.本来想直接用3074的.然后MLE,,,就差那么20M的空间,,. 从这里学习到了解法: http://www.cnblogs.com/ylfdrib/archive/2010/10/06/1844785.html…

DLX算法,刚接触,是关于精确覆盖的,白书上有算法介绍. 代码模板 #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <string.h> #include <vector> using namespace std; char puzzle[20][20]; const int SLOT=0; const int…

POJ 3074 : Description In the game of Sudoku, you are given a large 9 × 9 grid divided into smaller 3 × 3 subgrids. For example, . 2 7 3 8 . . 1 . . 1 . . . 6 7 3 5 . . . . . . . 2 9 3 . 5 6 9 2 . 8 . . . . . . . . . . . 6 . 1 7 4 5 . 3 6 4 . . . . .…

DLX用于优化精确覆盖问题,由于普通的DFS暴力搜索会超时,DLX是一个很强有力的优化手段,其实DLX的原理很简单,就是利用十字链表的快速删除和恢复特点,在DFS时删除一些行和列以减小查找规模,使得搜索深度越深而越小,然后回溯继续查找.具体资料可[点击这里]. 精确覆盖问题(补充):具体一点儿就是给你一个0-1矩阵,要你找出一些行,使得每一列都有且只有一个1. HUST 1017 Exact cover 入门必做,测试模板. #include <stdio.h> #include <st…

对于数独问题 ; //3*3数独 ; // 一格能填9个数 9*9格 +; // 9*9*4=(9+9+9)*9+9*9 (9+9+9)是9行 9列 9格 *9是9个数 9*9是81个格子 +MaxM+; char g[MaxN]; struct DLX { int n, m, size; int U[maxnode], D[maxnode], R[maxnode], L[maxnode], Row[maxnode], Col[maxnode]; int H[MaxN], S[MaxM]; //…

Dancing Links 本周的AI引论作业布置了一道数独 加了奇怪剪枝仍然TLE的Candy?不得不去学了dlx dlxnb! Exact cover 设全集X,X的若干子集的集合为S.精确覆盖是指,选择一个S的子集S',满足X中的每一个元素在S'中恰好出现一次. 是一个NPC问题. 可以表示成01矩阵形式,选择若干行,使得每一列恰好有且仅有一行为1. Sudoku 数独可以转化为精确覆盖问题. 令N=81为数独中格子个数,则: (x, y)=1表示(x,y)处填了数 (x+N, z)=1表…

一些链接: http://www.cnblogs.com/-sunshine/p/3358922.html http://www.cnblogs.com/grenet/p/3145800.html 1.hust 1017 Exact cover (Dancing Links 模板题) 题意:n*m的单位矩阵.现在要选一些行,使得这些行的集合中每列只出现一个1. 思路:裸的精确覆盖问题.刷一遍模板. #include <iostream> #include <stdio.h> #in…

DLX第一题,模板留念. /* 3076 */ #include <iostream> #include <string> #include <map> #include <queue> #include <set> #include <stack> #include <vector> #include <deque> #include <algorithm> #include <cstdio…

思路:记录每行每列每一个宫已经出现的数字就可以.数据比較弱 另外POJ 3074 3076 必须用剪枝策略.但实现较麻烦,还是以后学了DLX再来做吧 //Accepted 160K 0MS #include<cstdio> #include<iostream> #include<algorithm> #include<cstring> using namespace std; const int N =15; char sudo[N][N]; bool vi…

Halloween treats Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 7644   Accepted: 2798   Special Judge Description Every year there is the same problem at Halloween: Each neighbour is only willing to give a certain total number of sweets…

Find a multiple Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 7192   Accepted: 3138   Special Judge Description The input contains N natural (i.e. positive integer) numbers ( N <= 10000 ). Each of that numbers is not greater than 15000…

The Pilots Brothers' refrigerator Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 22286   Accepted: 8603   Special Judge Description The game “The Pilots Brothers: following the stripy elephant” has a quest where a player needs to open a…

Flip Game Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 37427   Accepted: 16288 Description Flip game is played on a rectangular 4x4 field with two-sided pieces placed on each of its 16 squares. One side of each piece is white and the…

Corn Fields Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 9806   Accepted: 5185 Description Farmer John has purchased a lush new rectangular pasture composed of M by N (1 ≤ M ≤ 12; 1 ≤ N ≤ 12) square parcels. He wants to grow some yumm…

Sum of Consecutive Prime Numbers Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 20050   Accepted: 10989 Description Some positive integers can be represented by a sum of one or more consecutive prime numbers. How many such representatio…

Tree Recovery Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 11939   Accepted: 7493 Description Little Valentine liked playing with binary trees very much. Her favorite game was constructing randomly looking binary trees with capital le…

Seek the Name, Seek the Fame Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 17898   Accepted: 9197 Description The little cat is so famous, that many couples tramp over hill and dale to Byteland, and asked the little cat to give names t…

题目: poj 2352 Stars 数星星 题意:已知n个星星的坐标.每个星星都有一个等级,数值等于坐标系内纵坐标和横坐标皆不大于它的星星的个数.星星的坐标按照纵坐标从小到大的顺序给出,纵坐标相同时则按照横坐标从小到大输出. (0 <= x, y <= 32000) 要求输出等级0到n-1之间各等级的星星个数. 分析: 这道题不难想到n平方的算法,即从纵坐标最小的开始搜,每次找它前面横坐标的值比它小的点的个数,两个for循环搞定,但是会超时. 所以需要用一些数据结构去优化,主要是优化找 横坐…

poj   1251  Jungle Roads  (最小生成树) Link: http://poj.org/problem?id=1251 Jungle Roads Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 23507   Accepted: 11012 Description The Head Elder of the tropical island of Lagrishan has a problem. A b…

Kaka's Matrix Travels Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 9567   Accepted: 3888 Description On an N × N chessboard with a non-negative number in each grid, Kaka starts his matrix travels with SUM = 0. For each travel, Kaka mo…

Friendship Time Limit: 2000MS   Memory Limit: 20000K Total Submissions: 10626   Accepted: 2949 Description In modern society, each person has his own friends. Since all the people are very busy, they communicate with each other only by phone. You can…

Ikki's Story I - Road Reconstruction Time Limit: 2000MS   Memory Limit: 131072K Total Submissions: 7659   Accepted: 2215 Description Ikki is the king of a small country – Phoenix, Phoenix is so small that there is only one city that is responsible fo…