P3818 小A和uim之大逃离 II-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_46709784/article/details/118871186

本文介绍了一个基于广度优先搜索(BFS)算法解决迷宫寻路问题的方法，特别考虑了瞬移这一特殊移动方式。通过增加状态维度来记录瞬移使用情况，实现了有效的路径搜索。

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难度：4
知识点：广度优先搜索

这个题只要状态想对了就很简单，状态再加上一维，就是到了这个点用过瞬移的次数，显然第三维只有0和1两种

#include <bits/stdc++.h>

#define fi first
#define se second
#define pb push_back
#define sz(x) ((int) x.size())
#define all(x) (x).begin(), (x).end()

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pa;

const int N = 1005;

struct node {
    int x, y, t;
    node(int a, int b, int c): x(a), y(b), t(c) {}
};

int n, m, d, r;
int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
string s[N];

void bfs() {
    queue<node> q;
    q.push(node(0, 0, 0));
    int dist[N][N][2];
    fill((int*) dist, (int*) dist + N * N * 2, -1);
    dist[0][0][0] = 0;
    while(!q.empty()) {
        node now = q.front(); q.pop();
        if (now.x == n - 1 && now.y == m - 1) {
            cout << dist[now.x][now.y][now.t]; return;
        }
        for (int i = 0; i < 4; i++) {
            int x = now.x + dx[i], y = now.y + dy[i];
            if (x < 0 || y < 0 || x >= n || y >= m || dist[x][y][now.t] > -1 || s[x][y] == '#') continue;
            q.push(node(x, y, now.t)); dist[x][y][now.t] = dist[now.x][now.y][now.t] + 1;
        }
        if (now.t == 0) {
            int x = now.x + d, y = now.y + r;
            if (x < 0 || y < 0 || x >= n || y >= m || dist[x][y][1] > -1 || s[x][y] == '#') continue;
            q.push(node(x, y, 1)); dist[x][y][1] = dist[now.x][now.y][0] + 1;
        }
    }
    cout << -1;
}

int main() {
    cin >> n >> m >> d >> r;
    for (int i = 0; i < n; i++) cin >> s[i];
    bfs();
    return 0;
}