宽度优先搜索 之 CODE[VS] 1026 逃跑的拉尔夫

/*
读懂题意，bfs即可AC。
不过注意“超出空间 Memory Limit Exceeded”，需要记录节点的状态，判重。
bool isUsed[i][j][k] := 是否之前已在第k步走到（i, j）的节点，是则true，否则false // 用于判重
*/

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstddef>
#include <iterator>
#include <algorithm>
#include <string>
#include <locale>
#include <cmath>
#include <vector>
#include <cstring>
#include <map>
#include <queue>
#include <stack>
#include <set>
using namespace std;
const int INF = -0x3f3f3f3f;
const int MaxN = 55;
const int modPrime = 3046721; 

int step[4][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
                //  北       南      西       东
int R, C;
int N;
struct Node
{
    int x;
    int y;
    int stepCnt;
};

Node startOff;
char imap[MaxN][MaxN];
string direction[1010];
bool isUsed[MaxN][MaxN][1010];

int getDirection(string str)
{
    if (str == "NORTH") return 0;
    if (str == "SOUTH") return 1;
    if (str == "WEST") return 2;
    if (str == "EAST") return 3;
    return -1;
}

void outPut()
{
    for (int i = 0; i < R; ++i)
    {
        for (int j = 0; j < C; ++j)
        {
            cout << imap[i][j];
        }
        cout << endl;
    }
}

void Solve()
{
    queue<Node> queNode;
    queNode.push(startOff);
    while (!queNode.empty())
    {
        Node node = queNode.front();
        queNode.pop();
        if (node.stepCnt == (N - 1))
        {
            imap[node.x][node.y] = '*';
            continue;
        }
        int num = getDirection(direction[node.stepCnt+1]);
        int x = node.x + step[num][0];
        int y = node.y + step[num][1];
        while ((x >= 0) && (x < R) && (y >= 0) && (y < C) && (imap[x][y] != 'X'))
        {
            Node nodeTmp;
            nodeTmp.x = x;
            nodeTmp.y = y;
            nodeTmp.stepCnt = node.stepCnt + 1;
            if (!isUsed[nodeTmp.x][nodeTmp.y][nodeTmp.stepCnt])
            {
                queNode.push(nodeTmp);
                isUsed[nodeTmp.x][nodeTmp.y][nodeTmp.stepCnt] = true;
            }
            x = x + step[num][0];
            y = y + step[num][1];
        }
    }

    outPut();
}


int main() 
{
#ifdef HOME
    freopen("in", "r", stdin);
    //freopen("out", "w", stdout);
#endif

    memset(isUsed, false, sizeof(isUsed));
    cin >> R >> C;
    bool getGoal = false;
    for (int i = 0; i < R; ++i)
    {
        cin >> imap[i];
        if (!getGoal)
        {
            for (int j = 0; j < C; ++j)
            {
                if (imap[i][j] == '*')
                {
                    imap[i][j] = '.';
                    startOff.x = i;
                    startOff.y = j;
                    startOff.stepCnt = -1;
                    getGoal = true;
                    break;
                }
            }
        }
    }
    cin >> N;
    for (int i = 0; i < N; ++i)
    {
        cin >> direction[i];
    }
    Solve();


#ifdef HOME
    cerr << "Time elapsed: " << clock() / CLOCKS_PER_SEC << " ms" << endl;
    _CrtDumpMemoryLeaks();
#endif
    return 0;
}