From c87154cdc14fe3d249baa63b75bf1065755aea7c Mon Sep 17 00:00:00 2001
From: Devesh511 <36008010+Devesh511@users.noreply.github.com>
Date: Wed, 23 Oct 2019 22:25:32 +0530
Subject: [PATCH] Create ValidPath.cpp

---
 Graphs/ValidPath.cpp | 60 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Graphs/ValidPath.cpp

diff --git a/Graphs/ValidPath.cpp b/Graphs/ValidPath.cpp
new file mode 100644
index 0000000..93d7de4
--- /dev/null
+++ b/Graphs/ValidPath.cpp
@@ -0,0 +1,60 @@
+//https://www.interviewbit.com/problems/valid-path/
+
+int dx[] = {0, 0, 1, 1, 1, -1, -1, -1};
+int dy[] = {1, -1, 1, 0, -1, 1, 0, -1};
+
+bool issafe(int x1, int y1, int x2, int y2, int r)
+{
+    int d = ((x1 - x2) * (x1 - x2)) + ((y1 - y2) * (y1 - y2));
+    int r2 = r * r;
+    return (d > r2);
+}
+
+bool isin(int x, int y, int r, int c)
+{
+    if((x < 0) || (y < 0) || (x > r) || (y > c))
+        return false;
+    return true;    
+}
+
+void dfs(int x, int y, int r, int c, vector<vector<bool> >&safe, vector<vector<bool> >&visited)
+{
+    if(!safe[x][y])
+        return;
+        
+    visited[x][y] = true;   
+    
+    for(int i = 0; i < 8; i++)
+    {
+        int nx = x + dx[i], ny = y + dy[i];
+        
+        if(isin(nx, ny, r, c) && (!visited[nx][ny]))
+            dfs(nx, ny, r, c, safe, visited);
+    }
+}
+
+string Solution::solve(int r, int c, int n, int R, vector<int> &X, vector<int> &Y) 
+{
+    vector<vector<bool> > safe(r + 1, vector <bool> (c + 1, true));
+    vector<vector<bool> > visited(r + 1, vector <bool> (c + 1, false));
+    
+    for(int i = 0; i <= r; i++)
+    {
+        for(int j = 0; j <= c; j++)
+        {
+            for(int k = 0; k < n; k++)
+            {
+                safe[i][j] = issafe(i, j, X[k], Y[k], R);
+                
+                if(!safe[i][j])
+                    break;
+            }
+        }
+    }
+    
+    dfs(0, 0, r, c, safe, visited);
+    
+    if(visited[r][c])
+        return string ("YES");
+    return string ("NO");    
+}