chore(CPlusPlus): add special index in an array (#1048)

Co-authored-by: Arsenic <54987647+Arsenic-ATG@users.noreply.github.com>

algorithms/CPlusPlus/Arrays/specialindex2.cpp

@@ -0,0 +1,65 @@
+/*
+@author: nandinisahu407
+special index-> if after deleting element from index i , sum of even index=sum of odd index
+approach->
+after deleting ,previous element at odd index will be now at even index and vice versa
+s_odd= odd[0 to i]+ even[i+1 to len]
+s_even=even[0 to i]+odd[i+1 to len]
+
+*/
+#include<iostream>
+using namespace std;
+ 
+int main(){
+    int num;
+    cout<<"enter length"<<endl;
+    cin>>num;
+    vector <int> arr (num);
+
+    for(int i=0;i<num;i++){
+        cin>>arr[i];
+    }
+
+    int count=0;
+    int s_even,s_odd;
+    for(int i=0;i<num;i++){ //checking whether special index or not
+        s_even=0,s_odd=0;
+
+        for(int j=0;j<i;j++){   // from index[0,i]
+            if(j%2==0){
+                s_even+=arr[j];
+            }
+            else{
+                s_odd+=arr[j];
+            }
+        }
+        for(int j=i+1;j<num;j++){    //from index[i+1,len]
+            if(j%2==0){
+                s_odd+=arr[j];
+            }
+            else{
+                s_even+=arr[j];
+            }
+        }
+
+        if(s_even==s_odd){    //checking whether sum of even index=sum of odd index
+            cout<<"\n special index found at: "<<i;
+            count++;
+        }
+        else{
+            continue;
+        }
+
+    }
+    cout<<"\n total special index: "<<count;   //displaying
+    return 0;
+}
+/* ----INPUT-----
+enter length 6
+4 3 2 7 6 -2
+----- OUTPUT------
+special index found at: 0
+special index found at: 2
+total special index:2
+*/
+//time complexity:o(n^2)

algorithms/CPlusPlus/README.md

@@ -32,6 +32,7 @@
 - [Maximum Minimum Average of numbers](Arrays/max-min-avg.cpp)
 - [Sparse Matrix](Arrays/sparse_matrix.cpp)
 - [Balanced Parenthesis](Arrays/balanced-parenthesis.cpp)
+- [Find special index](Arrays/specialindex2.cpp)
 
 
 ## Dynamic-Programming