题目链接
#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <cstdlib>#include <queue>using namespace std;const int maxn = 110;const int INF = 0x3f3f3f3f;int n, m, tot;int grid[maxn][maxn], dist[maxn][maxn], dp[1 << 12][20], vis[maxn][maxn];int dx[4] = { 1,0,0,-1 };int dy[4] = { 0,1,-1,0 };struct Point{ int x, y; Point(){} Point(int _x, int _y) :x(_x), y(_y){}}poi[maxn];struct Node{ int x, y, dist; Node(int _x,int _y,int _dist):x(_x),y(_y),dist(_dist){}};int BFS(int Start, int End){ memset(vis, false, sizeof(vis)); queue<Node> que; que.push(Node(poi[Start].x, poi[Start].y, 0)); int step, x, y; while (!que.empty()) { Node front = que.front(); que.pop(); if (front.x == poi[End].x&&front.y == poi[End].y) return front.dist; for (int i = 0; i < 4; i++) { int nowx = front.x + dx[i]; int nowy = front.y + dy[i]; if (nowx < 1 || nowx > n || nowy < 1 | nowy > m || grid[nowx][nowy] < 0) continue; if (!vis[nowx][nowy]) { vis[nowx][nowy] = 1; step = front.dist + 1; que.push(Node(nowx, nowy, step)); } } } return -1;}bool GetDist(){ memset(dist, 0, sizeof(dist)); for (int i = 0; i <= tot; i++) { for (int j = 0; j < i; j++) { dist[i][j] = dist[j][i]=BFS(i,j); if (dist[i][j] == -1) return false; } } return true;}int TSP(){ memset(dp, INF, sizeof(dp)); dp[1][0] = 0; int End = (1 << (tot+1))-1 ; for (int st = 0; st <= End; st++) { for (int i = 0; i <= tot; i++) { for (int j = 0; j <= tot; j++) { if (i == j) continue; if ((1 << i)&st == 0 || (1 << j)&st == 1) continue; if (dp[st][i] == INF) continue; dp[st | (1 << j)][j] = min(dp[st | (1 << j)][j], dp[st][i] + dist[i][j]); } } } if (dp[End][0] == INF) dp[End][0] = -1; return dp[End][0];}int main() { while (scanf("%d%d", &n, &m)!=EOF) { tot = 0; for (int i = 1; i <=n; i++) { for (int j = 1; j <= m; j++) { scanf("%d", &grid[i][j]); if (i + j == 2) continue; if (grid[i][j] > 0) poi[++tot] = Point(i, j); } } if (tot == 0) { printf("0\n"); continue; } poi[0] = Point(1, 1); if (grid[1][1] < 0 || !GetDist()) { printf("-1\n"); continue; } printf("%d\n", TSP()); } return 0;}
