Path With Minimum Effort

#define p pair< int, pair<int,int> >
class Solution {
public:
    int minimumEffortPath(vector<vector<int>>& heights) {
        int n=heights.size();
        int m=heights[0].size();
        vector<vector<int>>dist(n,vector<int>(m,1e9));
        dist[0][0]=0;
        priority_queue<p,vector<p>,greater<p>>minh;
        minh.push({0,{0,0}});//{patheffort, {x, y}}

        int dir[][2]={{-1,0},{0,-1},{1,0},{0,1}};

        while(!minh.empty()){
            auto node= minh.top();
            minh.pop();
            int patheffort=node.first;
            int x= node.second.first;
            int y= node.second.second;
            if(x==n-1 && y==m-1){
                return patheffort;
            }
            for(int i=0;i<4;i++){
                int nx=x+dir[i][0];
                int ny=y+dir[i][1];
                if(nx>=0 && ny>=0 && nx<n && ny <m && max(patheffort , abs(heights[nx][ny]-heights[x][y])) < dist[nx][ny]){
                    dist[nx][ny]=max(patheffort , abs(heights[nx][ny]-heights[x][y]));
                    minh.push({dist[nx][ny],{nx,ny}});
                }
            }
        }
        return -1;

        
    }
};