D. Igor In the Museum(简单DFS)

先预处理出每一个联通块的答案,然后查询时就可以O(1)出答案;

/* ***********************************************Author        :xdloveCreated Time  :2015年11月15日 星期日 16时47分40秒File Name     :xdlove/codeforces/Educational_Codeforces_Round_1/D/D.cpp************************************************ */#pragma comment(linker, "/STACK:1024000000,1024000000")#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <memory.h>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <math.h>#include <stdlib.h>#include <time.h>using namespace std;#define REP_ab(i,a,b) for(int i = a; i <= b; i++)#define REP(i, n) for(int i = 0; i < n; i++)#define REP_1(i,n) for(int i = 1; i <= n; i++)#define DEP(i,n) for(int i = n - 1; i >= 0; i--)#define DEP_N(i,n) for(int i = n; i >= 1; i--)#define CPY(A,B) memcpy(A,B,sizeof(B))#define MEM(A) memset(A,0,sizeof(A))#define MEM_1(A) memset(A,-1,sizeof(A))#define MEM_INF(A) memset(A,0x3f,sizeof(A))#define MEM_INFLL(A) memset(A,0x3f3f,sizeof(A))#define mid (((l + r) >> 1))#define lson l, mid, u << 1#define rson mid + 1, r, u << 1 | 1#define ls (u << 1)#define rs (u << 1 | 1)typedef long long ll;typedef unsigned long long ull;const int INF = 0x3f3f3f3f;const ll INFLL = 0x3f3f3f3f3f3f3f3f;const int MAXN = 1e3 + 5;const int MAXM = MAXN;const int mod = 1e9 + 7;char s[MAXN][MAXN];int n,m,k;int vis[MAXN][MAXN];int res[MAXN * MAXN];int dx[] = {    0,0,-1,1};int dy[] = {    -1,1,0,0};int id;bool check(int x,int y){    if(x < 0 || y < 0 || x >= n || y >= m || vis[x][y]) return false;    return true;}int dfs(int x,int y){    vis[x][y] = id;    int cnt = 0;    for(int i = 0; i < 4; i++)    {        int nx = dx[i] + x;        int ny = dy[i] + y;        if(check(nx,ny))        {            if(s[nx][ny] != '.') cnt++;            else cnt += dfs(nx,ny);        }    }    return cnt;}int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    cin>>n>>m>>k;    REP(i,n) scanf("%s",s[i]);    id = 1;    MEM(vis);    REP(i,n)     {        REP(j,m)        {            if(s[i][j] == '.' && !vis[i][j])            {                res[id] = dfs(i,j);                id++;            }        }    }    while(k--)    {        int x,y;        scanf("%d %d",&x,&y);        x--,y--;        printf("%d\n",res[vis[x][y]]);    }    return 0;}