pku 1164 the castle 深度搜索 解题报告

简单的dfs：

#include<iostream>
using namespace std;
const int MAXN = 55;

int count, a[MAXN][MAXN], used[MAXN][MAXN];

void dfs(int i, int j)
{
 used[i][j] = 1;
 ++count;
 if (a[i][j] % 2 == 0)       //向西的方向
 {
  if (!used[i][j - 1])
  {
   dfs(i, j - 1);
  }
 }
 a[i][j] /= 2;    
 if (a[i][j] % 2 == 0)     //向北的方向
 {
  if (!used[i - 1][j]) 
  {
   dfs(i - 1, j);
  }
 }
 a[i][j] /= 2;
 if (a[i][j] % 2 == 0)    //向东的方向
 {
  if (!used[i][j + 1]) 
  {
   dfs(i, j + 1);
  }
 }
 a[i][j] /= 2;
 if (a[i][j] % 2 == 0)  //向南的方向
 {
  if (!used[i + 1][j]) 
  {
   dfs(i + 1,j);
  }
 }
}

int main()
{
 //freopen("1.txt", "r", stdin);
 int i, j, r, c;
    
 scanf("%d%d", &r, &c);
 for (i = 1; i <= r; i ++) 
 {
  for (j = 1; j <= c; j ++)
  {
   scanf("%d", &a[i][j]); 
   used[i][j] = 0;
  }
  used[i][0] = used[i][c + 1] = 1;
 }
    for (j = 0; j <= c + 1; j++)
 {
  used[0][j] = used[r + 1][j] = 1;
 }
 int max = 0, num = 0;
 for (i = 1; i <= r; i++)
 {
  for (j = 1; j <= c; j++)
  {
   if (!used[i][j])
   {
    count = 0;
    num++;
    dfs(i, j);
    if (count > max)
    {
     max = count;
    }
   }
  }
 }
 printf("%d/n%d/n", num, max);
 
 return 0;
}