Flip Game(枚举)Poj
Flip Game
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 31329 | Accepted: 13622 |
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 other one is black and each piece is lying either it's black or white side up. Each
round you flip 3 to 5 pieces, thus changing the color of their upper side from black to white and vice versa. The pieces to be flipped are chosen every round according to the following rules:
Consider the following position as an example:
bwbw
wwww
bbwb
- Choose any one of the 16 pieces.
- Flip the chosen piece and also all adjacent pieces to the left, to the right, to the top, and to the bottom of the chosen piece (if there are any).
![](http://poj.org/images/1753_1.jpg)
bwbw
wwww
bbwb
bwwb
Here "b" denotes pieces lying their black side up and "w" denotes pieces lying their white side up. If we choose to flip the 1st piece from the 3rd row (this choice is shown at the picture), then the field will become:
bwbw
bwww
wwwb
wwwb
The goal of the game is to flip either all pieces white side up or all pieces black side up. You are to write a program that will search for the minimum number of rounds needed to achieve this goal.
Here "b" denotes pieces lying their black side up and "w" denotes pieces lying their white side up. If we choose to flip the 1st piece from the 3rd row (this choice is shown at the picture), then the field will become:
bwbw
bwww
wwwb
wwwb
The goal of the game is to flip either all pieces white side up or all pieces black side up. You are to write a program that will search for the minimum number of rounds needed to achieve this goal.
Input
The input consists of 4 lines with 4 characters "w" or "b" each that denote game field position.
Output
Write to the output file a single integer number - the minimum number of rounds needed to achieve the goal of the game from the given position. If the goal is initially achieved, then write 0. If it's impossible to achieve the
goal, then write the word "Impossible" (without quotes).
Sample Input
bwwb bbwb bwwb bwww
Sample Output
4
题意:有16个硬币 每一个硬币哟两种颜色(黑色b白色w),翻转当中不论什么一个硬币。其上下左右的硬币也要翻转,要求翻转最少的次数使全部的硬币达到同一种颜色,否则输出Impossible
艾玛 做了好长时间 加上大牛们的见解(让1为黑色 0为白色) 最终做出来了
#include <stdio.h> #include <string.h> #include <stdlib.h> #include <iostream> using namespace std; #define inf 9999999 int map[20][20]; int min_dis=inf; void change(int x,int y//翻转棋子 { map[x][y]=1-map[x][y]; map[x+1][y]=1-map[x+1][y]; if(x>0) map[x-1][y]=1-map[x-1][y]; map[x][y+1]=1-map[x][y+1]; if(y>0) map[x][y-1]=1-map[x][y-1]; } int check()//查看是否是同一颜色 { int i,j; int cnt=0; for(i=0;i<4;i++) for(j=0;j<4;j++) cnt+=map[i][j]; if(cnt==0||cnt==16)//棋盘为全白或全黑 return 1; else return 0; } void search(int d,int step) { int x,y; if(d==16) { if(check()&&step<min_dis) { min_dis=step; } } else { x=d/4; y=d%4; search(d+1,step); change(x,y); search(d+1,step+1); change(x,y); } } int main() { char str; int i,j; for(i=0;i<4;i++) for(j=0;j<4;j++) { cin>>str; if(str=='b') map[i][j]=1; else map[i][j]=0; } search(0,0); if(min_dis == inf) printf("Impossible\n"); else printf("%d\n",min_dis); return 0; }