题意
$5\times 7$ 版本的折纸小鸟对对碰,并且规定了只有 $n$ 次操作( $n\le 5$ )。
题解
注意到数据范围极小,不难想到暴力,但是直接暴力递归算出来微超。
所以考虑剪枝,最重要的剪枝就是判断无解,简单来说,当一种存在的颜色小于等于两种时,很显然不能再消去了,无解。
代码
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| #include<bits/stdc++.h> using namespace std;
typedef long long ll;
typedef pair<int , int > pii; typedef unsigned long long ull;
namespace FastIO { template<typename T> inline T read(T& x) { x = 0; int f = 1; char ch; while (!isdigit(ch = getchar())) if (ch == '-') f = -1; while (isdigit(ch)) x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar(); x *= f; return x; } template<typename T, typename... Args> inline void read(T& x, Args &...x_) { read(x); read(x_...); return; } inline ll read() { ll x; read(x); return x; } }; using namespace FastIO;
const int dx[2] = {1, -1};
int n; int a[10][10][10];
inline void Input() { read(n); int x; for(int i = 1; i <= 5; i++) { for(int j = 1; j <= 8; j++) { read(x); if(x == 0) break; a[0][i][j] = x; } } }
struct Node { int x, y, g; Node(int x = 0, int y = 0, int g = 0) : x(x), y(y), g(g) {} }; vector<Node >opt;
inline bool Empty(int tmp); inline void Copy(int tmp); inline void Down(int tmp); inline bool Clear(int tmp); inline bool Check(int tmp);
inline void Dfs(int cnt) { if(cnt == n + 1) { if(Empty(cnt - 1)) { for(auto &p : opt) { printf("%d %d %d\n", p.x, p.y, p.g); } return exit(0); } return ; } for(int r = 1; r <= 5; r++) { for(int c = 1; c <= 7; c++) { if(a[cnt-1][r][c] == 0) continue; for(int k = 0; k < 2; k++) { Copy(cnt); int nr = r + dx[k]; if(nr < 1 || nr > 5 || a[cnt][r][c] == a[cnt][nr][c]) continue; if(k == 1 && a[cnt][r][c] && a[cnt][nr][c]) continue; swap(a[cnt][r][c], a[cnt][nr][c]); do { Down(cnt); }while(Clear(cnt)); if(Check(cnt)) continue; opt.push_back(Node(r-1, c-1, dx[k])); Dfs(cnt + 1); opt.pop_back(); } } } }
inline void Work() { Dfs(1); printf("-1\n"); }
int main() { int T = 1; while(T--) { Input(); Work(); } return 0; }
inline bool Empty(int tmp) { for(int i = 1; i <= 5; i++) { for(int j = 1; j <= 7; j++) { if(a[tmp][i][j] != 0) return false; } } return true; } inline void Copy(int tmp) { for(int i = 1; i <= 5; i++) { for(int j = 1; j <= 7; j++) { a[tmp][i][j] = a[tmp-1][i][j]; } } } inline void Down(int tmp) { for(int i = 1; i <= 5; i++) { int p[10], cnt = 0; for(int j = 1; j <= 7; j++) { if(a[tmp][i][j]) { p[++cnt] = a[tmp][i][j]; } a[tmp][i][j] = 0; } for(int j = 1; j <= cnt; j++) { a[tmp][i][j] = p[j]; } } } int vis[10][10]; inline void Checkx(int tmp, int i, int j) { if(a[tmp][i][j] == 0) return ; if(a[tmp][i+1][j] != a[tmp][i][j]) return ; if(a[tmp][i+2][j] != a[tmp][i][j]) return ; vis[i][j] = vis[i+1][j] = vis[i+2][j] = 1; } inline void Checky(int tmp, int i, int j) { if(a[tmp][i][j] == 0) return ; if(a[tmp][i][j+1] != a[tmp][i][j]) return ; if(a[tmp][i][j+2] != a[tmp][i][j]) return ; vis[i][j] = vis[i][j+1] = vis[i][j+2] = 1; } inline bool Clear(int tmp) { bool flag = 0; for(int i = 1; i <= 5; i++) { for(int j = 1; j <= 7; j++) { vis[i][j] = 0; } } for(int i = 1; i <= 5; i++) { for(int j = 1; j <= 5; j++) { Checky(tmp, i, j); } } for(int j = 1; j <= 7; j++) { for(int i = 1; i <= 3; i++) { Checkx(tmp, i, j); } } for(int i = 1; i <= 5; i++) { for(int j = 1; j <= 7; j++) { if(vis[i][j]) { a[tmp][i][j] = 0, flag = 1; } } } return flag; } inline bool Check(int tmp) { int p[15]; for(int i = 1; i <= 10; i++) p[i] = 0; for(int i = 1; i <= 5; i++) { for(int j = 1; j <= 7; j++) { p[a[tmp][i][j]]++; } } for(int i = 1; i <= 10; i++) { if(p[i] != 0 && p[i] < 3) return true; } return false; }
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