From e33542139f78bd4f60180d4cde9a93fc47323e85 Mon Sep 17 00:00:00 2001
From: Mohit Yadav <mohityadav1921@gmail.com>
Date: Sun, 5 Nov 2017 02:51:25 +0530
Subject: [PATCH] Added Number of Islands

---
 Code Sheets/Graph/Number of Islands.txt | 48 +++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Code Sheets/Graph/Number of Islands.txt

diff --git a/Code Sheets/Graph/Number of Islands.txt b/Code Sheets/Graph/Number of Islands.txt
new file mode 100644
index 0000000..96d5ff0
--- /dev/null
+++ b/Code Sheets/Graph/Number of Islands.txt	
@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+bool isVisited[500][500] = {false}; //array to keep track of visited nodes
+int n,m; //no. of rows and columns
+int a[500][500]; //input matrix
+int islandCount=0; //number of islands
+
+void dfs(int x, int y){
+    isVisited[x][y] = true;
+
+    //utility arrays to make the traversing easy
+    int posX[] = {-1, -1, -1, 0, 0, 1, 1, 1};
+    int posY[] = {-1, 0, 1, -1, 1, -1, 0, 1};
+
+    for(int i=0; i<8; i++){
+        int p = x+posX[i], q = y+posY[i];
+        if(p>=0 && p<n && q>=0 && q<m){
+            if(a[p][q] == 1 && !isVisited[p][q]){
+                dfs(p,q);
+            }
+        }
+    }
+}
+
+int main()
+{
+    cin>>n>>m;
+    for(int i=0; i<n; i++){
+        getchar();
+        for(int j=0; j<m; j++){
+            a[i][j] = getchar()-48;
+        }
+    }
+
+    //counting the number of islands
+    for(int i=0; i<n; i++){
+        for(int j=0; j<m; j++){
+            if(a[i][j] == 1 && !isVisited[i][j]){
+                dfs(i,j);
+                islandCount++;
+            }
+        }
+    }
+    cout<<islandCount;
+
+    return 0;
+}