Online JudgeProblem SetAuthorsOnline ContestsUser
Web Board
Home Page
Statistical Charts
Submit Problem
Online Status
Update your info
Authors ranklist
Current Contest
Past Contests
Scheduled Contests
Award Contest
User ID:
欢迎参加IJCAI 2020麻将智能体竞赛,大奖等你拿!Welcome to IJCAI 2020 Mahjong AI competition with amazing prizes! | 北京大学《ACM/ICPC大学生程序设计竞赛训练》暑期课面向全球招生!
Time Limit: 1000MSMemory Limit: 65536K
Total Submissions: 709Accepted: 247


Flood-it is a fascinating puzzle game on Google+ platform. The game interface is like follows:

At the beginning of the game, system will randomly generate an N×N square board and each grid of the board is painted by one of the six colors. The player starts from the top left corner. At each step, he/she selects a color and changes all the grids connected with the top left corner to that specific color. The statement “two grids are connected” means that there is a path between the certain two grids under condition that each pair of adjacent grids on this path is in the same color and shares an edge. In this way the player can flood areas of the board from the starting grid (top left corner) until all of the grids are in same color. The following figure shows the earliest steps of a 4×4 game (colors are labeled in 0 to 5):

Given a colored board at very beginning, please find the minimal number of steps to win the game (to change all the grids into a same color).


The input contains no more than 20 test cases. For each test case, the first line contains a single integer N (2<=N<=8) indicating the size of game board.

The following N lines show an N×N matrix (ai,j)n×n representing the game board. ai,j is in the range of 0 to 5 representing the color of the corresponding grid.

The input ends with N = 0.


For each test case, output a single integer representing the minimal number of steps to win the game.

Sample Input

0 0 
0 0
0 1 2
1 1 2
2 2 1

Sample Output



[Submit]   [Go Back]   [Status]   [Discuss]

Home Page   Go Back  To top

All Rights Reserved 2003-2013 Ying Fuchen,Xu Pengcheng,Xie Di
Any problem, Please Contact Administrator