POJ3984 迷宫问题

典型BFS。

#include <iostream>

#include <memory.h>

#include <queue>

#include <map>



#define LEN 5

using namespace std;



int graph[LEN][LEN];

int ans = 0;

int dx[4] = {-1, 1, 0, 0};

int dy[4] = {0, 0, -1, 1};



void printAns(map<int, int> &visit, int p) {

    if (p == -1) return;

    int prev = visit[p];

    printAns(visit, prev);

    int x = p / 5;

    int y = p - x * 5;

    cout << "(" << x << ", " << y << ")" << endl;

}



int main()

{

    memset(graph, 0, sizeof(graph));

    int n = 5;

    for (int i = 0; i < n; i++) {

        for (int j = 0; j < n; j++) {

            cin >> graph[i][j];

        }

    }

    queue<int> que; // (3,4) is 3*5+4 = 19

    map<int, int> visit; // points to it's prev    

    que.push(0);

    visit[0] = -1;    

    int dest = 4 * 5 + 4;    

    while (!que.empty()) {

        int point = que.front();

        que.pop();

        if (point == dest) break;

        int x = point / 5;

        int y = point - x * 5;

        for (int i = 0; i < 4; i++) {

            int next_x = x + dx[i];

            int next_y = y + dy[i];

            if (next_x >= 5 || next_x < 0 || next_y >=5 || next_y < 0) continue;

            if (graph[next_x][next_y] == 1) continue;

            int key = next_x * 5 + next_y;

            if (visit.count(key) != 0) continue;

            visit[key] = point;

            que.push(key);

        }

    }

    

    // print ans from dest

    printAns(visit, dest);

    return 0;

}