E - Bishop 2

https://atcoder.jp/contests/abc246/tasks/abc246_e

思想

BFS遍历。

Code

https://atcoder.jp/contests/abc246/submissions/38443616

 
bool pts[1505][1505]; // if blocked
bool vis[1505][1505]; // visited
bool add[1505][1505]; // added
int mvs[1505][1505]; // num of moves
 
int n;
int ax, ay;
int bx, by;
 
typedef struct node{
    int x;
    int y;
} NODE;
 
int main()
{
    cin >> n;
    cin >> ax >> ay;
    cin >> bx >> by;
    
    for(int i=0; i<n; i++){
        string si;
        cin >> si;
        
        for(int j=0; j<n; j++){
            char one = si[j];
            if (one == '.'){
                pts[i+1][j+1] = true;
            } else if(one == '#'){
                pts[i+1][j+1] = false;
            }
            
            mvs[i+1][j+1] = -1;
            vis[i+1][j+1] = false;
            add[i+1][j+1] = false;
        }
    }
 
    NODE one;
    one.x = ax;
    one.y = ay;
    
    queue<NODE> qq;
    qq.push(one);
    mvs[ax][ay] = 0;
    add[ax][ay] = true;
    
    while(!qq.empty()){
        NODE cur = qq.front();
        qq.pop();
 
        int x = cur.x;
        int y = cur.y;
        
        vis[x][y] = true;
//        cout << "visited. x=" << x << "y=" << y << endl;
        
        if (x == bx && y == by){
            cout << mvs[x][y] << endl;
               return 0;
        }
        
        int ix, iy;
        
        ix = x;
        iy = y;
        while(ix+1>=1
                && ix+1<=n
                && iy+1>=1
                && iy+1<=n
                && pts[ix+1][iy+1]){
            ix++;
            iy++;
            
            if (vis[ix][iy]){
                continue;
            }
 
            if (add[ix][iy]){
                continue;
            }
 
            NODE one;
            one.x = ix;
            one.y = iy;
            qq.push(one);
            add[ix][iy] = true;
            
//            cout << "1-added. x=" << ix << "y=" << iy << endl;
            
            mvs[ix][iy] = mvs[x][y] + 1;
        }
 
        ix = x;
        iy = y;
        while(ix+1>=1
                && ix+1<=n
                && iy-1>=1
                && iy-1<=n
                && pts[ix+1][iy-1]){
            ix++;
            iy--;
 
            if (vis[ix][iy]){
                continue;
            }
 
            if (add[ix][iy]){
                continue;
            }
 
            NODE one;
            one.x = ix;
            one.y = iy;
            qq.push(one);
            add[ix][iy] = true;
            
//            cout << "2-added. x=" << ix << "y=" << iy << endl;
 
            mvs[ix][iy] = mvs[x][y] + 1;
        }
 
        ix = x;
        iy = y;
        while(ix-1>=1
                && ix-1<=n
                && iy+1>=1
                && iy+1<=n
                && pts[ix-1][iy+1]){
            ix--;
            iy++;
 
            if (vis[ix][iy]){
                continue;
            }
 
            if (add[ix][iy]){
                continue;
            }
 
            NODE one;
            one.x = ix;
            one.y = iy;
            qq.push(one);
            add[ix][iy] = true;
            
//            cout << "3-added. x=" << ix << "y=" << iy << endl;
 
            mvs[ix][iy] = mvs[x][y] + 1;
        }
 
        ix = x;
        iy = y;
        while(ix-1>=1
                && ix-1<=n
                && iy-1>=1
                && iy-1<=n
                && pts[ix-1][iy-1]){
            ix--;
            iy--;
 
            if (vis[ix][iy]){
                continue;
            }
 
            if (add[ix][iy]){
                continue;
            }
 
            NODE one;
            one.x = ix;
            one.y = iy;
            qq.push(one);
            add[ix][iy] = true;
            
//            cout << "4-added. x=" << ix << "y=" << iy << endl;
 
            mvs[ix][iy] = mvs[x][y] + 1;
        }
    }
 
    cout << -1 << endl;
 
    return 0;
}