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- #include <iostream>
- #include <queue>
- #include <cstring>
- #include <fstream>
- #include <vector>
- using namespace std;
- int n, m;
- char mat[1001][1001];
- int si, sj;
- int ei, ej;
- int dist[1001][1001];
- vector<pair<int, int> > guards;
- const int di[] = {-1, 1, 0, 0};
- const int dj[] = {0, 0, -1, 1};
- bool visited[1001][1001];
- struct node{
- int ii, jj, cost;
- node(){}
- node(int _ii, int _jj, int _cost){
- ii = _ii;
- jj = _jj;
- cost = _cost;
- }
- bool operator < (const node &a)const{
- return cost < a.cost;
- }
- };
- int main()
- {
- ios_base::sync_with_stdio(false);
- cin >> n >> m;
- for(int i = 0; i < n; i ++){
- for(int j = 0; j < m; j ++){
- cin >> mat[i][j];
- if(mat[i][j] == 'R'){
- si = i;
- sj = j;
- }
- if(mat[i][j] == 'Z'){
- ei = i;
- ej = j;
- }
- if(mat[i][j] == 'G'){
- guards.push_back(make_pair(i, j));
- }
- }
- }
- queue<int> q;
- memset(dist, -1, sizeof dist);
- for(int i =0; i < guards.size(); i ++){
- q.push(guards[i].first);
- q.push(guards[i].second);
- dist[guards[i].first][guards[i].second] = 0;
- }
- memset(visited, false, sizeof visited);
- int ii, jj, ni, nj;
- while(!q.empty()){
- ii = q.front();
- q.pop();
- jj = q.front();
- q.pop();
- for(int k =0; k < 4; k ++){
- ni = di[k] + ii;
- nj = dj[k] + jj;
- if(ni < 0 || nj < 0 || ni >= n || nj >= m)continue;
- if(dist[ni][nj] != -1)continue;
- if(mat[ni][nj] == '*')continue;
- dist[ni][nj] = dist[ii][jj] + 1;
- q.push(ni);
- q.push(nj);
- }
- }
- priority_queue<node> pq;
- pq.push(node(si, sj, dist[si][sj]));
- visited[si][sj] = true;
- node tmp;
- while(!pq.empty()){
- tmp = pq.top();
- pq.pop();
- if(tmp.ii == ei && tmp.jj == ej){
- cout << tmp.cost << endl;
- break;
- }
- for(int k = 0; k < 4; k ++){
- ni = di[k] + tmp.ii;
- nj = dj[k] + tmp.jj;
- if(ni < 0 || nj < 0 || ni >= n || nj >= m)continue;
- if(visited[ni][nj])continue;
- if(mat[ni][nj] == '*')continue;
- visited[ni][nj] = true;
- pq.push(node(ni, nj, min(tmp.cost, dist[ni][nj])));
- }
- }
- return 0;
- }
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