Completed Graph-1

ballinaMaze.cpp

@@ -0,0 +1,43 @@
+#include<iostream>
+#include<bits/stdc++.h>
+#include<vector>
+using namespace std;
+/*
+We keep rolling the ball in all directions until it hits a wall, starting from the current position.
+Each time we land on a new stopping cell, we check if it's the destination and then DFS from there.
+We mark visited cells as -1 to avoid revisiting the same paths again.
+*/
+class Solution{
+    vector<vector<int>> dirs;
+    int m, n;
+
+    bool dfs(vector<vector<int>>& maze, int i, int j, vector<int>& destination){
+        if(destination[0] == i && destination[1] == j) return true;
+        if(maze[i][j] == -1) return false;
+
+        maze[i][j] = -1;
+        for(auto& dir : dirs){
+            int r = dir[0] + i;
+            int c = dir[1] + j;
+
+            while(r >= 0 && c >= 0 && r < m && c < n && maze[r][c] != 1){
+                r += dir[0];
+                c += dir[1];
+            }
+
+            r -= dir[0];
+            c -= dir[1];
+
+            if(dfs(maze, r, c, destination)) return true;
+        }
+        return false;
+    }
+public:
+    bool hasPath(vector<vector<int>>& maze, vector<int>& start, vector<int>& destination){
+        dirs = {{-1, 0}, {1,0}, {0,1}, {0, -1}};
+        m = maze.size();
+        n = maze[0].size();
+
+        return dfs(maze, start[0], start[1], destination);
+    }
+};

townJudge.cpp

@@ -0,0 +1,25 @@
+#include<iostream>
+#include<bits/stdc++.h>
+#include<vector>
+using namespace std;
+/*
+We use an array to count trust levels: losing trust (out-degree) subtracts, gaining trust (in-degree) adds.
+The town judge should be trusted by everyone else but trust no one.
+So we just find the person with an in-degree of n−1.
+*/
+class Solution{
+public:
+    int findJudge(int n, vector<vector<int>>& trust){
+        vector<int> inDegrees(n+1);
+
+        for(auto& it : trust){
+            inDegrees[it[0]]--;
+            inDegrees[it[1]]++;
+        }
+
+        for(int i = 0; i <= n; i++){
+            if(inDegrees[i] == n-1) return i;
+        }
+        return -1;
+    }
+};