POJ3690 Constellations 【KMP】

Constellations

Time Limit: 3000MS		Memory Limit: 65536K
Total Submissions: 5044		Accepted: 983

Description

The starry sky in the summer night is one of the most beautiful things on this planet. People imagine that some groups of stars in the sky form so-called constellations. Formally a constellation is a group of stars that are connected together to form a figure
or picture. Some well-known constellations contain striking and familiar patterns of bright stars. Examples are Orion (containing a figure of a hunter), Leo (containing bright stars outlining the form of a lion), Scorpius (a scorpion), and Crux (a cross).

In this problem, you are to find occurrences of given constellations in a starry sky. For the sake of simplicity, the starry sky is given as a N × M matrix, each cell of which is a '*' or '0' indicating a star in the corresponding position
or no star, respectively. Several constellations are given as a group of T P × Q matrices. You are to report how many constellations appear in the starry sky.

Note that a constellation appears in the sky if and only the corresponding P × Q matrix exactly matches some P × Q sub-matrix in the N × M matrix.

Input

The input consists of multiple test cases. Each test case starts with a line containing five integers N, M, T, P and Q(1 ≤ N, M ≤ 1000, 1 ≤ T ≤ 100, 1 ≤ P, Q ≤ 50). 

The following N lines describe the N × M matrix, each of which contains M characters '*' or '0'.

The last part of the test case describe T constellations, each of which takes P lines in the same format as the matrix describing the sky. There is a blank line preceding each constellation.

The last test case is followed by a line containing five zeros.

Output

For each test case, print a line containing the test case number( beginning with 1) followed by the number of constellations appearing in the sky.

Sample Input

3 3 2 2 2
*00
0**
*00

**
00

*0
**
3 3 2 2 2
*00
0**
*00

**
00

*0
0*
0 0 0 0 0

Sample Output

Case 1: 1
Case 2: 2

题意：给定一个n行m列的01矩阵。再给定t个p行q列的小01矩阵，求这t个小矩阵有多少个在大矩阵中。

题解：这题我用的是KMP，先把矩阵二进制压缩成整型数组，再求整型数组的next数组，再去跟压缩后的大矩阵匹配。遗憾的是TLE了。

。

这题先就这样放着，等以后学了AC自己主动机再试试。

#include <stdio.h>
#define maxn 1002
#define maxm 52

char bigMap[maxn][maxn], smallMap[maxm][maxm];
__int64 smallToInt[maxm], hash[maxn][maxn];
int m, n, t, p, q, next[maxm];

void toInt64(int i, int j)
{
    __int64 sum = 0;
    for(int k = 0; k < p; ++k)
        if(bigMap[i + k][j] == '*') sum = sum << 1 | 1;
        else sum <<= 1;
    hash[i][j] = sum;
}

void charToHash()
{
    int i, j, temp = n - p;
    for(i = 0; i <= temp; ++i){
        for(j = 0; j < m; ++j) toInt64(i, j);
    }
}

void getNext()
{
    __int64 sum;
    int i, j;
    for(i = 0; i < q; ++i){
        for(sum = j = 0; j < p; ++j)
            if(smallMap[j][i] == '*') sum = sum << 1 | 1;
            else sum <<= 1;
        smallToInt[i] = sum;
    }
    i = 0; j = -1;
    next[0] = -1;
    while(i < q){
        if(j == -1 || smallToInt[i] == smallToInt[j]){
            ++i; ++j;
            if(smallToInt[i] == smallToInt[j]) next[i] = next[j];
            else next[i] = j; //mode 2
        }else j = next[j];
    }
}

bool KMP()
{
    getNext();
    int i, j, k, temp = n - p;
    for(k = 0; k <= temp; ++k){
        i = j = 0;
        while(i < m && j < q){
            if(j == -1 || hash[k][i] == smallToInt[j]){
                ++i; ++j;
            }else j = next[j];
        }
        if(j == q) return true;
    }
    return false;
}

int main()
{
   // freopen("stdin.txt", "r", stdin);
    int i, j, ans, cas = 1;
    while(scanf("%d%d%d%d%d", &n, &m, &t, &p, &q) != EOF){
        if(m + n + t + p + q == 0) break;
        for(i = 0; i < n; ++i)
            scanf("%s", bigMap[i]);
        charToHash(); ans = 0;
        while(t--){
            for(i = 0; i < p; ++i)
                scanf("%s", smallMap[i]);
            if(KMP()) ++ans;
        }
        printf("Case %d: %d\n", cas++, ans);
    }
    return 0;
}