POJ

Corn Fields

Time Limit: 2000MS Memory Limit: 65536KTotal Submissions: 17037 Accepted: 8998

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 yummy corn for the cows on a number of squares. Regrettably, some of the squares are infertile and can't be planted. Canny FJ knows that the cows dislike eating close to each other, so when choosing which squares to plant, he avoids choosing squares that are adjacent; no two chosen squares share an edge. He has not yet made the final choice as to which squares to plant.

Being a very open-minded man, Farmer John wants to consider all possible options for how to choose the squares for planting. He is so open-minded that he considers choosing no squares as a valid option! Please help Farmer John determine the number of ways he can choose the squares to plant.

Input

Line 1: Two space-separated integers: M and N 
Lines 2..M+1: Line i+1 describes row i of the pasture with N space-separated integers indicating whether a square is fertile (1 for fertile, 0 for infertile)

Output

Line 1: One integer: the number of ways that FJ can choose the squares modulo 100,000,000.

Sample Input

2 31 1 10 1 0

Sample Output

9

Hint

Number the squares as follows:

1 2 3  4  

There are four ways to plant only on one squares (1, 2, 3, or 4), three ways to plant on two squares (13, 14, or 34), 1 way to plant on three squares (134), and one way to plant on no squares. 4+3+1+1=9.

Source

USACO 2006 November Gold

题意：有n*m块土地，1为肥沃的，0为不肥沃的，只能在肥沃的土地上种植，且每个种植的土地上下左右四块土地不能再继续种植，问共有多少种方法种植

利用递推，从上一状态推到下一状态

#include <iostream>#include <string.h>#include <stdio.h>using namespace std;#define LL long longconst int N = 5e3+10;const int mod = 1e8;int n,m,a,b[15];LL dp[15][N];int main(){    while(scanf("%d%d",&n,&m)!=EOF){        memset(dp,0,sizeof dp);        for(int i=1;i<=n;i++){            b[i] = 0;            for(int j=1;j<=m;j++){                scanf("%d",&a);                b[i] <<= 1;                b[i] += a;            }        }        dp[0][0] = 1;        for(int i=1;i<=n;i++){            for(int j=0;j<1<<m;j++){                if(j&(j<<1)||((j|b[i])!=b[i])) continue;                for(int k=0;k<1<<m;k++){                    if(j&k||((k|b[i-1])!=b[i-1])) continue;                    dp[i][j] += dp[i-1][k];                    dp[i][j] %= mod;                }            }        }        LL ans = 0;        for(int i=0;i<1<<m;i++){            ans += dp[n][i];            ans %= mod;        }        printf("%lld\n",ans);    }    return 0;}