CSES Grid Paths
// compile: g++ -o data data.cpp -std=gnu++20 -DLOCAL
// run: ./data < data.in
#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#endif
#define sz(v) ((int)(v).size())
#define PV(v) for (int i=0;i<v.size();++i)cout<<v[i]<<" ";cout<<endl;
#define INTINF 9223372036854775807
#define int long long

using namespace std;

int dir[4][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
int n = 7;
int vis[9][9];
int s[100];
int cnt, total = 0;

bool ok(int x, int y) {
    return !vis[x][y];
}

bool iswall(int x, int y) {
    return !(x>=1 && y>=1 && x<=n && y<=n);
}

void dfs(int x, int y, int k) {
    if (x==n && y==1 && k>=n*n) {
        if (cnt == n*n) ++total;
        return;
    }
    if ((x==n-1 && y==0) || k>=n*n) return;
    // if (vis[x + dir[pre][0]][y + dir[pre][1]]) {
    //     int l = (pre - 1) % 4, r = (pre + 1) % 4;
    //     if (!vis[x + dir[l][0]][y + dir[l][1]] && !vis[x + dir[r][0]][y + dir[r][1]]) return;
    // }
    for (int i = 0; i < 4; ++i) {
        int l = (i - 1) % 4, r = (i + 1) % 4, oppo = (i + 2) % 4;
        if (vis[x + dir[i][0]][y + dir[i][1]] && vis[x + dir[oppo][0]][y + dir[oppo][1]] && !vis[x + dir[l][0]][y + dir[l][1]] && !vis[x + dir[r][0]][y + dir[r][1]]) return;
    }
    if (~s[k]) {
        int i = s[k];
        if (vis[x + dir[i][0]][y + dir[i][1]]) return;
        vis[x + dir[i][0]][y + dir[i][1]] = 1;
        ++cnt;
        dfs(x + dir[i][0], y + dir[i][1], k + 1);
        --cnt;
        vis[x + dir[i][0]][y + dir[i][1]] = 0;
        return;
    }
    int dx = -1, dy = -1, m = 0;
    for (int i = 0; i < 4; ++i) {
        int xx = x + dir[i][0], yy = y + dir[i][1];
        if (vis[xx][yy] || (xx == n && yy == 1)) continue;
        int total = 0;
        for (int j = 0; j < 4; ++j) total += vis[xx + dir[j][0]][yy + dir[j][1]];
        if (total == 3) {
            ++m;
            dx = xx;
            dy = yy;
        }
    }
    if (m > 1) return;
    if (m == 1) {
        vis[dx][dy] = 1;
        ++cnt;
        dfs(dx, dy, k + 1);
        --cnt;
        vis[dx][dy] = 0;
        return;
    }
    for (int i = 0; i < 4; ++i) {
        if (vis[x + dir[i][0]][y + dir[i][1]]) continue;
        vis[x + dir[i][0]][y + dir[i][1]] = 1;
        ++cnt;
        dfs(x + dir[i][0], y + dir[i][1], k + 1);
        --cnt;
        vis[x + dir[i][0]][y + dir[i][1]] = 0;
    }
}

int32_t main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    for (int i = 1; i < n*n; ++i) {
        char ch; cin >> ch;
        if (ch == '?') s[i] = -1;
        else if (ch == 'R') s[i] = 0;
        else if (ch == 'D') s[i] = 1;
        else if (ch == 'L') s[i] = 2;
        else if (ch == 'U') s[i] = 3;
    }
    vis[1][1] = 1;
    for (int i = 0; i <= (n+1); ++i) {
        vis[0][i] = vis[i][0] = vis[n+1][i] = vis[i][n+1] = 1;
    }
    cnt = 1;
    dfs(1, 1, 1);
    cout << total << endl;

    return 0;
}
No Comments

Send Comment Edit Comment


				
|´・ω・)ノ
ヾ(≧∇≦*)ゝ
(☆ω☆)
(╯‵□′)╯︵┴─┴
 ̄﹃ ̄
(/ω\)
∠( ᐛ 」∠)_
(๑•̀ㅁ•́ฅ)
→_→
୧(๑•̀⌄•́๑)૭
٩(ˊᗜˋ*)و
(ノ°ο°)ノ
(´இ皿இ`)
⌇●﹏●⌇
(ฅ´ω`ฅ)
(╯°A°)╯︵○○○
φ( ̄∇ ̄o)
ヾ(´・ ・`。)ノ"
( ง ᵒ̌皿ᵒ̌)ง⁼³₌₃
(ó﹏ò。)
Σ(っ °Д °;)っ
( ,,´・ω・)ノ"(´っω・`。)
╮(╯▽╰)╭
o(*////▽////*)q
>﹏<
( ๑´•ω•) "(ㆆᴗㆆ)
😂
😀
😅
😊
🙂
🙃
😌
😍
😘
😜
😝
😏
😒
🙄
😳
😡
😔
😫
😱
😭
💩
👻
🙌
🖕
👍
👫
👬
👭
🌚
🌝
🙈
💊
😶
🙏
🍦
🍉
😣
Source: github.com/k4yt3x/flowerhd
颜文字
Emoji
小恐龙
花!
Previous
Next