feat: Add solutions for Codeforces problems 1991 A, B, and C

Codes/1991 A - Maximize the Last Element/1991A.cpp

@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+using namespace std;
+#ifdef ONLINE_JUDGE
+#define dbg(...)
+#else
+#include "Assets/debug.h"
+#endif
+#define  int  long long
+#define  ll  long long
+#define  endl  '\n'
+#define  ff  first
+#define  ss  second
+#define  ins  insert
+#define  pb  push_back
+#define  ppb  pop_back
+#define  sz(x)  (int)(x).size()
+#define  all(x)  x.begin(), x.end()
+#define  rep(i,a,b)  for(int i=a; i<b; ++i)
+#define  rrep(i,a,b) for(int i=a; i>=b; --i)
+#define  yn(f)  f? cout<<"YES\n":cout<<"NO\n"
+#define  FAST  (ios_base::sync_with_stdio(false), cin.tie(nullptr));
+ll pow(ll x,ll y,ll m=1e9+7) {ll ans=1;x%=m;while(y){if(y&1)ans=(ans*x)%m;x=(x*x)%m;y>>=1;}return ans;}
+
+void solve()
+{
+    int n;
+    cin>>n;
+    int mx=0;
+    for(int i=1; i<=n; ++i)
+    {
+        int x;
+        cin>>x;
+        if(i&1) mx=max(mx,x);
+    }
+    cout<<mx<<endl;
+}
+
+signed main()
+{
+    FAST;
+    int TCS = 1;
+    cin >> TCS;
+    for (int TC = 1; TC <= TCS; ++TC)
+    {
+      // cout<<"Case "<<TC<<": ";
+      solve();
+    }
+}

Codes/1991 B - AND Reconstruction/1991B.cpp

@@ -0,0 +1,58 @@
+#include <bits/stdc++.h>
+using namespace std;
+#ifdef ONLINE_JUDGE
+#define dbg(...)
+#else
+#include "Assets/debug.h"
+#endif
+#define  int  long long
+#define  ll  long long
+#define  endl  '\n'
+#define  ff  first
+#define  ss  second
+#define  ins  insert
+#define  pb  push_back
+#define  ppb  pop_back
+#define  sz(x)  (int)(x).size()
+#define  all(x)  x.begin(), x.end()
+#define  rep(i,a,b)  for(int i=a; i<b; ++i)
+#define  rrep(i,a,b) for(int i=a; i>=b; --i)
+#define  yn(f)  f? cout<<"YES\n":cout<<"NO\n"
+#define  FAST  (ios_base::sync_with_stdio(false), cin.tie(nullptr));
+ll pow(ll x,ll y,ll m=1e9+7) {ll ans=1;x%=m;while(y){if(y&1)ans=(ans*x)%m;x=(x*x)%m;y>>=1;}return ans;}
+
+void solve()
+{
+    int n;
+    cin >> n;
+    vector<int> b(n-1);
+    vector<int> a(n);
+    rep(i, 0, n-1) cin >> b[i];
+    a[0] = b[0];
+    rep(i, 1, n-1) a[i] = b[i-1] | b[i];
+    a[n-1] = b[n-2];
+    rep(i,1,n)
+    {
+        int x=a[i]&a[i-1];
+        int y=b[i-1];
+        if(x!=y)
+        {
+            cout<<-1<<endl;
+            return;
+        }
+    }
+    rep(i, 0, n) cout << a[i] << " ";
+    cout << endl;
+}
+
+signed main()
+{
+    FAST;
+    int TCS = 1;
+    cin >> TCS;
+    for (int TC = 1; TC <= TCS; ++TC)
+    {
+      // cout<<"Case "<<TC<<": ";
+      solve();
+    }
+}

Codes/1991 C - Absolute Zero/1991C.cpp

@@ -0,0 +1,61 @@
+#include <bits/stdc++.h>
+using namespace std;
+#ifdef ONLINE_JUDGE
+#define dbg(...)
+#else
+#include "Assets/debug.h"
+#endif
+#define  int  long long
+#define  ll  long long
+#define  endl  '\n'
+#define  ff  first
+#define  ss  second
+#define  ins  insert
+#define  pb  push_back
+#define  ppb  pop_back
+#define  sz(x)  (int)(x).size()
+#define  all(x)  x.begin(), x.end()
+#define  rep(i,a,b)  for(int i=a; i<b; ++i)
+#define  rrep(i,a,b) for(int i=a; i>=b; --i)
+#define  yn(f)  f? cout<<"YES\n":cout<<"NO\n"
+#define  FAST  (ios_base::sync_with_stdio(false), cin.tie(nullptr));
+ll pow(ll x,ll y,ll m=1e9+7) {ll ans=1;x%=m;while(y){if(y&1)ans=(ans*x)%m;x=(x*x)%m;y>>=1;}return ans;}
+
+void solve()
+{
+    int n;
+    cin>>n;
+    bool even=0,odd=0;
+    rep(i,0,n)
+    {
+        int x;
+        cin>>x;
+        if(x&1)
+            odd=1;
+        else 
+            even=1;
+    }
+    if(even && odd)
+    {
+        cout<<-1<<endl;
+        return;
+    }
+    vector<int>ans;
+    rrep(i,29,0)   ans.pb(1<<i);
+    if(even)    ans.pb(1);
+    cout<<ans.size()<<endl;
+    for(auto x:ans) cout<<x<<" ";
+    cout<<endl;
+}
+
+signed main()
+{
+    FAST;
+    int TCS = 1;
+    cin >> TCS;
+    for (int TC = 1; TC <= TCS; ++TC)
+    {
+      // cout<<"Case "<<TC<<": ";
+      solve();
+    }
+}

Readme.md

@@ -367,13 +367,16 @@ This repository contains my solutions of Codeforces problems. They are in C++ la
 | 355 | 1989 A | Catch the Coin | [Question](https://codeforces.com/problemset/problem/1989/A) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1989%20A%20-%20Catch%20the%20Coin)
 | 356 | 1989 B | Substring and Subsequence | [Question](https://codeforces.com/problemset/problem/1989/B) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1989%20B%20-%20Substring%20and%20Subsequence)
 | 357 | 1989 C | Two Movies | [Question](https://codeforces.com/problemset/problem/1989/C) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1989%20C%20-%20Two%20Movies)
-| 358 | 1992 A | Only Pluses | [Question](https://codeforces.com/problemset/problem/1992/A) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1992%20A%20-%20Only%20Pluses)
+| 358 | 1991 A | Maximize the Last Element | [Question](https://codeforces.com/problemset/problem/1991/A) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1991%20A%20-%20Maximize%20the%20Last%20Element)
-| 359 | 1992 B | Angry Monk | [Question](https://codeforces.com/problemset/problem/1992/B) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1992%20B%20-%20Angry%20Monk)
+| 359 | 1991 B | AND Reconstruction | [Question](https://codeforces.com/problemset/problem/1991/B) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1991%20B%20-%20AND%20Reconstruction)
-| 360 | 1992 C | Gorilla and Permutation | [Question](https://codeforces.com/problemset/problem/1992/C) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1992%20C%20-%20Gorilla%20and%20Permutation)
+| 360 | 1991 C | Absolute Zero | [Question](https://codeforces.com/problemset/problem/1991/C) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1991%20C%20-%20Absolute%20Zero)
-| 361 | 1996 A | Legs | [Question](https://codeforces.com/problemset/problem/1996/A) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20A%20-%20Legs)
+| 361 | 1992 A | Only Pluses | [Question](https://codeforces.com/problemset/problem/1992/A) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1992%20A%20-%20Only%20Pluses)
-| 362 | 1996 B | Scale | [Question](https://codeforces.com/problemset/problem/1996/B) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20B%20-%20Scale)
+| 362 | 1992 B | Angry Monk | [Question](https://codeforces.com/problemset/problem/1992/B) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1992%20B%20-%20Angry%20Monk)
-| 363 | 1996 C | Sort | [Question](https://codeforces.com/problemset/problem/1996/C) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20C%20-%20Sort)
+| 363 | 1992 C | Gorilla and Permutation | [Question](https://codeforces.com/problemset/problem/1992/C) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1992%20C%20-%20Gorilla%20and%20Permutation)
-| 364 | 1996 D | Fun | [Question](https://codeforces.com/problemset/problem/1996/D) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20D%20-%20Fun)
+| 364 | 1996 A | Legs | [Question](https://codeforces.com/problemset/problem/1996/A) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20A%20-%20Legs)
+| 365 | 1996 B | Scale | [Question](https://codeforces.com/problemset/problem/1996/B) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20B%20-%20Scale)
+| 366 | 1996 C | Sort | [Question](https://codeforces.com/problemset/problem/1996/C) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20C%20-%20Sort)
+| 367 | 1996 D | Fun | [Question](https://codeforces.com/problemset/problem/1996/D) | [Solution](https://github.com/ShazidMashrafi/Codeforces-Solutions/tree/master/Codes/1996%20D%20-%20Fun)