Added Flood fill Algorithm

Author: suraj0223

Graph/flood_fill.cpp

@@ -0,0 +1,62 @@
+//Problem statement
+// An image is represented by a 2-D array of integers,
+// each integer representing the pixel value of the image (from 0 to 65535).
+// Given a coordinate (sr, sc) representing the starting pixel 
+// (row and column) of the flood fill, and a pixel value newColor, "flood fill" the image.
+// To perform a "flood fill", consider the starting pixel,
+// plus any pixels connected 4-directionally to the starting pixel of the same
+//  color as the starting pixel, plus any pixels connected 4-directionally to those
+//  pixels (also with the same color as the starting pixel), and so on. Replace the
+//  color of all of the aforementioned pixels with the newColor.
+// At the end, return the modified image.
+
+#include<bits/stdc++.h>
+using namespace std;
+
+ vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor) {
+        
+        if(image[sr][sc] == newColor)
+            return image;
+        
+        queue<int> qx;
+        queue<int> qy;
+        
+        int rw = image.size();
+        int clm = image[0].size();
+        
+        qx.push(sr);
+        qy.push(sc);
+        
+        int curr = image[sr][sc];
+        image[sr][sc] = newColor;
+        
+        while( !qx.empty() ) {
+            
+            int x = qx.front();
+            int y = qy.front();
+            
+            qx.pop();
+            qy.pop();
+            
+            int arrx[] = {-1, 0, 1, 0};
+            int arry[] = {0, 1, 0, -1};
+            
+            for(int i=0; i<4; i++) {
+                
+                int tempx = x + arrx[i];
+                int tempy = y + arry[i];
+                
+                if(tempx <0 || tempy < 0) continue;
+                if(tempx >=rw || tempy >= clm) continue;
+                
+                if(image[tempx][tempy] == curr){
+                    qx.push(tempx);
+                    qy.push(tempy);
+                    image[tempx][tempy] = newColor;
+                }
+            }
+        }
+        
+        return image;
+    }
+