poj dfs相关之1753 Flip Game

poj dfs相关之1753 Flip Game

132K 313MS

#include<iostream>#include<cstring>#include<cstdio>#include<algorithm>#include<vector>#include<queue>using namespace std;int n, k, ans;bool IsFind, arr[6][6];int dir[4][2] = { { -1, 0 }, { 1, 0 }, { 0, -1 }, { 0, 1 } };bool check(){    int i, j, t;    t = arr[1][1];    for (i = 1; i <= 4;i++)    for (j = 1; j <= 4; j++)    {        if (t != arr[i][j])            return false;    }    return true;}void flip(int row, int col){    int i, x, y;    arr[row][col] = !arr[row][col];    for (i = 0; i < 4; i++)    {        x = row + dir[i][0];        y = col + dir[i][1];        arr[x][y] = !arr[x][y];    }}void dfs(int row,int col,int dep){    if (dep == ans)    {        if (check())            IsFind = true;        return;    }    if (row>4 || col > 4 || IsFind)        return;    flip(row, col);    if (col < 4)        dfs(row, col + 1, dep + 1);    else        dfs(row + 1, 1, dep + 1);    flip(row, col);    if (col < 4)        dfs(row, col + 1, dep);    else        dfs(row + 1, 1, dep);}int main(){    //freopen("1.txt", "r", stdin);    int i, j, tmp1, tmp2;    memset(arr, 0, sizeof(arr));    char tmp[15];    for (i = 1; i < 5; i++)    {        scanf("%s", tmp);        for (j = 1; j < 5; j++)        {            if (tmp[j - 1] == 'b')                arr[i][j] = 1;            else if (tmp[j - 1] == 'w')                arr[i][j] = 0;        }    }    for (i = 0; i <= 16; i++)    {        IsFind = false;        ans = i;        dfs(1, 1, 0);        if (IsFind)            break;    }    if(IsFind)        printf("%d\n", ans);    else        printf("Impossible\n");}

132K 125MS
这个是一个一次性枚举所有的版本，效率更高

#include<iostream>#include<cstring>#include<cstdio>#include<algorithm>#include<vector>#include<queue>using namespace std;int n, k, ans;bool IsFind, arr[6][6];int dir[4][2] = { { -1, 0 }, { 1, 0 }, { 0, -1 }, { 0, 1 } };bool check(){    int i, j, t;    t = arr[1][1];    for (i = 1; i <= 4;i++)    for (j = 1; j <= 4; j++)    {        if (t != arr[i][j])            return false;    }    return true;}void flip(int row, int col){    int i, x, y;    arr[row][col] = !arr[row][col];    for (i = 0; i < 4; i++)    {        x = row + dir[i][0];        y = col + dir[i][1];        arr[x][y] = !arr[x][y];    }}void dfs(int row,int col,int dep){    if (check())    {        ans = min(ans, dep);        return;    }    if (row>4 || col > 4 || IsFind)        return;    flip(row, col);    if (col < 4)        dfs(row, col + 1, dep + 1);    else        dfs(row + 1, 1, dep + 1);    flip(row, col);    if (col < 4)        dfs(row, col + 1, dep);    else        dfs(row + 1, 1, dep);}int main(){    freopen("1.txt", "r", stdin);    int i, j, tmp1, tmp2;    memset(arr, 0, sizeof(arr));    char tmp[15];    for (i = 1; i < 5; i++)    {        scanf("%s", tmp);        for (j = 1; j < 5; j++)        {            if (tmp[j - 1] == 'b')                arr[i][j] = 1;            else if (tmp[j - 1] == 'w')                arr[i][j] = 0;        }    }    ans = 17;    dfs(1, 1, 0);    if(ans<17)        printf("%d\n", ans);    else        printf("Impossible\n");}