Fire Net HDU 1045

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簡單深搜，可以完全暴力，不會逾時的。

#include<iostream>#include<cstring>#include<cmath>using namespace std;#define MAX(a,b) (a>b?a:b) char maze[10][10];int n, maxn;void DFS(int step,int count);int cheak(int x, int y);int main(){    int i;    while(scanf("%d",&n), n)    {        maxn = 0;        for(i = 0; i < n; i++)            scanf("%s",maze[i]);        DFS(0,0);        printf("%d\n",maxn);    }    return 0;}void DFS(int step,int count){    int x, y;    maxn = MAX(maxn,count);    if(step == n*n)        return ;    x = step/n;    y = step%n;    if(maze[x][y] == ‘.‘ && cheak(x,y))    {        maze[x][y] = ‘O‘;        DFS(step+1,count+1);        maze[x][y] = ‘.‘;    }    DFS(step + 1, count);}int cheak(int x, int y){    int i;    for(i = x-1; i >= 0; i--)    {        if(maze[i][y] == ‘O‘)            return 0;        else if(maze[i][y] == ‘X‘)            break;    }    for(i = y-1; i >= 0; i--)    {        if(maze[x][i] == ‘O‘)            return 0;        else if(maze[x][i] == ‘X‘)            break;    }    return 1;}