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;
}