Solved some problems

4 files changed, 117 insertions, 0 deletions

diff --git a/contests/Starters80/E/main b/contests/Starters80/E/main
new file mode 100755
index 0000000..6f8e448
--- /dev/null
+++ b/contests/Starters80/E/main
diff --git a/contests/Starters80/E/main.cpp b/contests/Starters80/E/main.cpp
new file mode 100755
index 0000000..c53ffef
--- /dev/null
+++ b/contests/Starters80/E/main.cpp
@@ -0,0 +1,110 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+using ll = long long;
+using pi = pair<int, int>;
+using vpi = vector<pi>;
+using vi = vector<int>;
+using vll = vector<long long>;
+using mpii = map<int, int>;
+using mpll = map<ll, ll>;
+using db = long double;
+
+#define pb push_back 
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+#define lb lower_bound
+#define ub upper_bound
+
+const int MOD = (int)1e9 + 7;
+const db PI = acos((db)-1);
+const int dx[4]{1, 0, -1, 0};
+const int dy[4]{0, 1, 0, -1};
+
+//pretty printing
+template<typename K, typename V>
+void printm(const map<K, V> &mp) {
+  cerr << "{" << endl;
+  for (auto p : mp) {
+    cerr << "  { " << p.first << " : " << p.second << " }\n";
+  }
+  cerr << "}" << endl;
+}
+template<typename T>
+void printv(const vector<T> &v) {
+  cerr << "[";
+  for (int i = 0; i < v.size(); i++) {
+    if (i == v.size() - 1) {
+      cerr << v[i];
+    } else {
+      cerr << v[i] << ", ";
+    }
+  }
+  cerr << "]\n";
+}
+
+template<typename T>
+void printvv(const vector<vector<T>> &v) {
+  cerr << "[\n";
+  for (auto &vec : v) {
+    cout << "  ";
+    printv(vec);
+  }
+  cerr << "]\n";
+}
+void print() {
+  cerr << "\n";
+}
+
+template<typename T, typename... TS>
+void print(T val, TS... vals) {
+  cerr << val << " ";
+  print(vals...);
+}
+
+
+/* stuff you should look for:
+  ---------------------------
+   * special cases (n=1?)
+   * int overflow, array bounds
+   * do smth instead of nothing and stay organized
+   * WRITE STUFF DOWN
+   * DON'T GET STUCK ON ONE APPROACH
+ */
+
+void solve() {
+
+  int n;
+  cin >> n;
+  vi v(n);
+  map<int, int> fq;
+  for (int i = 0; i < n; i++) {
+    int x;
+    cin >> x;
+    v[i] = x;
+    fq[x]++;
+  }
+  vll dp(n); 
+  dp[0] = fq[1];
+  for (int i = 1; i < n; i++) {
+    dp[i] = (dp[i - 1] * fq[i + 1]) % MOD;
+  }
+  ll sum = 0;
+  for (auto x : dp) {
+    sum = (sum + x) % MOD;
+  }
+  cout << sum << '\n';
+
+}
+
+int main () {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int tt;
+  cin >> tt;
+  while(tt--) {
+    solve();
+  }
+}
+
+
diff --git a/contests/Starters80/E/main_input0.txt b/contests/Starters80/E/main_input0.txt
new file mode 100644
index 0000000..8353715
--- /dev/null
+++ b/contests/Starters80/E/main_input0.txt
@@ -0,0 +1,5 @@
+2
+5
+1 2 3 2 4
+6
+1 3 5 8 9 8
diff --git a/contests/Starters80/E/main_output0.txt b/contests/Starters80/E/main_output0.txt
new file mode 100644
index 0000000..107b687
--- /dev/null
+++ b/contests/Starters80/E/main_output0.txt
@@ -0,0 +1,2 @@
+7
+1