From 52287febe41b26d5459b934d9aae8cb5c0b47342 Mon Sep 17 00:00:00 2001
From: msms <44134797+maitreyi0505@users.noreply.github.com>
Date: Tue, 6 Oct 2020 17:05:48 +0530
Subject: [PATCH] Create Flood Fill Algorithm (C++).cpp

Input for the code:
4 5
1 3 1 2 2
1 2 2 2 3
2 1 1 2 1
3 1 2 2 2
3 2
8

Output:
Updated screen after call to floodFill:
1 3 1 8 8
1 8 8 8 3
2 1 1 8 1
3 1 8 8 8
---
 .../Flood Fill Algorithm (C++).cpp            | 63 +++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 Flood Fill Algo/Flood Fill Algorithm (C++).cpp

diff --git a/Flood Fill Algo/Flood Fill Algorithm (C++).cpp b/Flood Fill Algo/Flood Fill Algorithm (C++).cpp
new file mode 100644
index 0000000..7ea18a3
--- /dev/null
+++ b/Flood Fill Algo/Flood Fill Algorithm (C++).cpp	
@@ -0,0 +1,63 @@
+// Flood fill algorithm in C++ using Queue
+
+#include <bits/stdc++.h>
+using namespace std;
+
+void checkAndPush(int x,int y, int r,  int c, int prevC, int newC, queue<pair<int,int>>&q, vector<vector<int>> &screen)
+{
+    if(x<0 || y<0 || x>=r || y>=c || screen[x][y]!=prevC)
+        return;
+    
+    screen[x][y]=newC;
+    q.push(make_pair(x,y));
+    return;
+}
+
+//Driver code
+int main() {
+    int r,c,i,j,x,y,prevC,newC;
+    queue<pair<int,int>>q;
+    pair<int, int> cur;
+    
+    cin>>r>>c;
+    vector<vector<int>> screen(r) ;
+    
+  //input the screen array
+	for(i=0;i<r;i++)
+	{
+	    vector<int>row(c);
+	    for(j=0;j<c;j++)
+	        cin>>row[j];
+	    screen[i]=row;
+	}
+	
+	cin>>x>>y;
+	prevC=screen[x][y];
+	
+	cin>>newC;
+    
+  //push first position pair to queue
+  checkAndPush(x,y,r,c,prevC,newC,q,screen);
+
+  while(!q.empty())
+  {
+      cur=q.front();
+      q.pop();
+      x=cur.first;
+      y=cur.second;
+
+      //fill adjacent cells
+      checkAndPush(x-1,y,r,c,prevC,newC,q,screen);
+      checkAndPush(x+1,y,r,c,prevC,newC,q,screen);
+      checkAndPush(x,y-1,r,c,prevC,newC,q,screen);
+      checkAndPush(x,y+1,r,c,prevC,newC,q,screen);
+  }
+  cout<<"Updated screen after call to floodFill: \n"; 
+  for (i = 0; i < r; i++) 
+  { 
+      for (j = 0; j < c; j++) 
+          cout<<screen[i][j]<<" "; 
+      cout<<endl; 
+  } 
+	return 0;
+}