孤岛营救问题 (BFS+状压)
BFS + 状压
写过就好想,注意细节debug
#include <bits/stdc++.h> #define read read() #define up(i,l,r) for(register int i = (l);i <= (r);i++) #define down(i,l,r) for(register int i = (l);i >= (r);i--) #define traversal_vedge(i) for(register int i = head[u]; i ;i = e[i].nxt) #define ll long long using namespace std; int read { int x = 0, f = 1; char ch = getchar(); while(ch < 48 || ch > 57) {if(ch == '-')f = -1; ch = getchar();} while(ch >=48 && ch <=57) {x = 10 * x + ch - 48;ch = getchar();} return x * f; } void write(int x) { if(x < 0) x = -x,putchar('-'); if(x > 9) write(x/10); putchar(x%10 + 48); } //----------------------------------------------------------------- const int N = 12; int n,m,p,k,s; int maps[N][N][N][N],cnt[N][N],type[N][N][N],vis[N][N][(1<<N)]; int dx[] = {0,0,0,-1,1},dy[] = {0,-1,1,0,0}; void readdata() { n = read; m = read; p = read; k = read; int x1,x2,y1,y2,G; while(k--) { x1 = read; y1 = read; x2 = read; y2 = read; G = read; if(G) maps[x1][y1][x2][y2] = maps[x2][y2][x1][y1] = G; else maps[x1][y1][x2][y2] = maps[x2][y2][x1][y1] = -1; } s = read; int q; while(s--) { x1 = read; x2 = read; q = read; type[x1][x2][++cnt[x1][x2]] = q; } } struct node{ int x,y,step,state; }; int get_state(int x,int y) { int ans = 0; up(i,1,cnt[x][y]) ans |= (1<<(type[x][y][i] - 1)); return ans; } int bfs() { queue <node> q; int s = get_state(1,1); q.push((node){1,1,0,s} ); vis[1][1][s] = 1; while(!q.empty()) { node u = q.front(); q.pop(); int x = u.x,y = u.y; if(x == n && y == m) return u.step; up(i,1,4) { int nx = x + dx[i],ny = y + dy[i]; if(nx < 1 || ny < 1 || nx > n || ny > m) continue; int obstacle = maps[x][y][nx][ny]; if(obstacle == -1) continue; if( obstacle > 0 && (u.state & 1<<(obstacle - 1)) == 0 ) continue;//debug obstacle - 1 <- 1 - obstacle int ns = u.state|get_state(nx,ny);//degug u.state <- s; if(vis[nx][ny][ns]) continue; vis[nx][ny][ns] = 1; q.push( (node){nx,ny,u.step+1,ns} ); } } return -1; } int main() { freopen("input.txt","r",stdin); readdata(); printf("%d\n",bfs()); return 0; }
