Walls and Gates

import java.util.* ; import java.io.*; class Pair<T> { T a; T b; public Pair(T a, T b){ this.a =a; this.b = b; } public T getKey(){ return a; } public T getValue(){ return b; } } public class Solution { public static int[][] wallsAndGates(int[][] a, int n, int m) { // dfs from gate to empty room Queue<Pair<Integer>> q = new LinkedList<>(); for(int i=0;i<n;i++){ for(int j = 0;j<m;j++){ if(a[i][j]==0){ q.add(new Pair(i,j)); } } } int dirs[][] = {{0,-1},{0,1},{-1,0},{1,0}}; while(!q.isEmpty()){ Pair<Integer> p = q.remove(); int iq = p.getKey(); int jq = p.getValue(); for(int dir[]: dirs){ int i = iq + dir[0]; int j = jq + dir[1]; if(i<n && j<m && i>=0 && j>=0 && a[i][j]== Integer.MAX_VALUE){ a[i][j] = a[iq][jq] +1; q.add(new Pair(i,j)); } } } return a; } // dfs from empty room to gate not recommended leading to TLE public static long update(int i, int j ,int[][] a, int n , int m,int [][] visited){ //base case if(a[i][j] ==0) return 0; //i,j is the emty room long min = Integer.MAX_VALUE; visited[i][j] = 1; int dirs[][] = {{0,-1},{0,1},{-1,0},{1,0}}; for(int dir[] : dirs){ int I = i+dir[0]; int J = j+dir[1]; if(I<n && J<m && I>=0 && J>=0 && a[I][J]!=-1 && visited[I][J]==0){ min = Math.min(min, Math.abs(I-i) + Math.abs(J-j) + update(I,J,a,n,m,visited)); } } visited[i][j] = 0; return min; } }