poj1979 Red and Black(dfs)

Red and Black

Time Limit: 1000MSMemory Limit: 30000KTotal

Submissions: 23001Accepted: 12407

问题

//1.遍历方式不对，连被红块堵在角落里的黑块都给遍历到了

1.二维数组长宽分不清

2.把ans++;room[nx][ny];放在控制范围内if语句里

3.填坑的时候有问题，room[x][y]应该填的是nx，ny

4.while(~scanf("%d%d",&w,&h),w+h)这个可以排除掉数组为0的情况还要加上#include<cstdio>

5.人家是要循环着交题，不能用if，

6.ans没有被更新，全局变量

#include <iostream>#include <cstdio>#define MAX_W 20#define MAX_H 20using namespace std;int W, H;char room[MAX_H][MAX_W + 1];int ans;int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};void print(){    for(int i = 0; i < H; i++)    {        for(int j = 0; j < W; j++)        {            cout << room[i][j];        }        cout << endl << endl;    }}void dfs(int x, int y){    for(int i = 0; i < 4; i++)    {        int nx = x + dx[i], ny = y + dy[i];        if(0 <= nx && nx < H && 0 <= ny && ny < W && room[nx][ny] == '.')        {            room[nx][ny] = '#';            //print();            ans ++;            dfs(nx, ny);        }    }    return;}void solve(){    for(int i = 0; i < H; i++)        for(int j = 0; j < W; j++)        {            if(room[i][j] == '@')                dfs(i, j);        }    cout << ans << endl;}int main(){    while(~scanf("%d%d",&W,&H),W + H)    {        for(int i = 0; i < H; i++)            for(int j = 0; j < W; j++)            {                cin >> room[i][j];            }        ans = 1;        solve();    }    return 0;}