chore: solved hard day 8 task

Hard/Day8/Solution.cpp

@@ -1 +1,38 @@
-// Write Your Code Here
+// Write Your Code Here
+#include<bits/stdc++.h>
+using namespace std;
+#define fast ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
+typedef long long int ll;
+
+int main()
+{
+    fast;
+    int T; cin >> T;
+    while(T--)
+    {
+      ll n,k; cin >> n >> k;
+      ll a[n];
+      for(ll i=0; i<n; i++){cin >> a[i];}
+      vector<ll>count(n,0);
+      ll flag = 0;
+
+      ll start = 0; ll end = n-1;
+      for(ll i=0; i<k; i++)
+      {
+        if(count[end] != 0){break;}
+        if(a[end]>n){flag++; break;}
+        count[end]++;
+        ll x = a[end];
+
+        start = (start-(x%n));
+        end = (end-(x%n));
+        if(end < 0){end = end+n;}
+        if(start < 0){start = start+n;}
+
+        ll y = (start+x-1)%n;
+        if(a[y] != x){flag++; break;}
+      }
+      if(flag == 0){cout << "YES" << endl;}
+      else{cout << "NO" << endl;}
+    }
+}