CF3A Shortest path of the king
CF3A Shortest path of the king
#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <queue> using namespace std; const int N = 10; int dx[8] = {1, 1, 0, -1, -1, -1, 0, 1}; int dy[8] = {0, 1, 1, 1, 0, -1, -1, -1}; string s[8] = {"U", "RU", "R", "RD", "D", "LD", "L", "LU"}; vector<string> ans; struct Node{ int x, y, step; }node, S, T; bool st[N][N]; int d[N][N]; Node q[N]; void bfs() { d[S.x][S.y] = 0; queue<Node> q; q.push(S); st[S.x][S.y] = true; while(q.size()) { Node t = q.front(); q.pop(); int x = t.x, y = t.y, step = t.step; d[x][y] = step; for(int i = 0; i < 8; i ++) { int nx = x + dx[i], ny = y + dy[i]; if(nx >= 0 && nx <= 7 && ny >= 0 && ny <= 7 && !st[nx][ny]) { node.x = nx, node.y = ny, node.step = step + 1; q.push(node); st[nx][ny] = true; } } } } void find(int x, int y) { for(int i = 0; i < 8; i ++) { if(x == dx[i] && y == dy[i]) ans.push_back(s[i]); } } int main() { char s1[3], s2[3]; cin >> s1 >> s2; S = {s1[1] - '1', s1[0] - 'a', 0}; T = { s2[1] - '1',s2[0] - 'a', 0}; bfs(); cout << d[T.x][T.y] << endl; int x = T.x, y = T.y; if(d[x][y] == 0) return 0; while(1) { bool flag = false; for(int i = 0; i < 8; i ++) { int nx = x + dx[i], ny = y + dy[i]; if(nx < 0 || nx > 7 || ny < 0 || ny > 7) continue; if(d[nx][ny] == 0) { find(x - nx, y - ny); flag = true; break; } if(d[nx][ny] == d[x][y] - 1) { find(x - nx, y - ny); x = nx, y = ny; continue; } } if(flag == true) break; } int len = ans.size() - 1; for(int i = len; i >= 0; i --) cout << ans[i] << endl; }