Create NPAIRS.java

CodeChef/NPAIRS.java

@@ -0,0 +1,66 @@
+/* package codechef; // don't place package name! */
+
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+/* Name of the class has to be "Main" only if the class is public. */
+class Codechef
+{
+	public static void main (String[] args) throws java.lang.Exception
+	{
+		// your code goes here
+		Scanner scan=new Scanner(System.in);
+		int T=scan.nextInt();
+		while(T-->0)
+		{
+		   int N=scan.nextInt();
+		   String s=scan.next();
+		   int count=0;
+		   HashMap<Integer, Integer> mp = new HashMap<>();
+		   HashMap<Integer, Integer> mpl = new HashMap<>();
+		   for(int i = 0; i < N; i++)
+            {
+                int val=Integer.parseInt(String.valueOf(s.charAt(i)));
+
+        // Stores count of distinct
+        // values of arr[i] - x * i
+        mp.put(val-i,
+               mp.getOrDefault(val-i, 0) + 1);
+
+            }
+             for(int i = 0; i < N; i++)
+            {
+                int val=Integer.parseInt(String.valueOf(s.charAt(i)));
+
+
+                mpl.put(val+i,
+              mpl.getOrDefault(val+i, 0) + 1);
+            }
+
+    // Iterate over the Map
+    for(int v : mp.values())
+    {
+
+        // Increase count of pairs
+       // System.out.print(v);
+
+        if(v>1)
+            count +=(v*(v-1)/2);
+    }
+    //System.out.println();
+     for(int v : mpl.values())
+    {
+
+        // Increase count of pairs
+
+       // System.out.print(v);
+        if(v>1)
+            count +=(v*(v-1)/2);
+    }
+    //System.out.println();
+    // Print the count of such pairs
+    System.out.println(count);
+		}
+	}
+}