edu round 69

Author: seunghyukcho

Codeforces/Educational Round/69/A.cpp

@@ -0,0 +1,27 @@
+#include <iostream>
+#include <algorithm>
+#include <vector>
+
+using namespace std;
+
+int main()
+{
+    int T;
+    for(cin >> T; T > 0; T--)
+    {
+        int n, num;
+        vector<int> planks;
+
+        cin >> n;
+        for(int i = 0; i < n; i++)
+        {
+            cin >> num;
+            planks.push_back(num);
+        }
+
+        sort(planks.begin(), planks.end());
+        int b1 = planks.back(), b2 = planks[n - 2];
+
+        cout << min(min(b1, b2) - 1, n - 2) << '\n';
+    }
+}

Codeforces/Educational Round/69/B.cpp

@@ -0,0 +1,34 @@
+#include <iostream>
+
+using namespace std;
+
+int n, disks[200002];
+
+int main()
+{
+    int mx[2] = { 0, 0 };
+
+    cin >> n;
+    for(int i = 0; i < n; i++)
+    {
+        cin >> disks[i];
+        if(mx[0] < disks[i])
+        {
+            mx[0] = disks[i];
+            mx[1] = i;
+        }
+    }
+
+    bool flag = true;
+    for(int i = 0; flag && i < mx[1]; i++)
+    {
+        if(disks[i] > disks[i + 1]) flag = false;
+    }
+
+    for(int i = mx[1]; flag && i < n - 1; i++)
+    {
+        if(disks[i] < disks[i + 1]) flag = false;
+    }
+
+    cout << (flag ? "YES" : "NO") << '\n';
+}

Codeforces/Educational Round/69/C.cpp

@@ -0,0 +1,27 @@
+#include <iostream>
+#include <algorithm>
+#include <queue>
+
+using namespace std;
+
+typedef long long ll;
+
+int n, k, a[300002];
+ll ans;
+
+int main()
+{
+    priority_queue<int> pq;
+    cin >> n >> k;
+    for(int i = 0; i < n; i++) cin >> a[i];
+    for(int i = 0; i < n - 1; i++) pq.push(a[i + 1] - a[i]);
+
+    ans += a[n - 1] - a[0];
+    for(; k > 1; k--)
+    {
+        int t = pq.top(); pq.pop();
+        ans -= t;
+    }
+
+    cout << ans << '\n';
+}

Codeforces/Educational Round/69/D.cpp

@@ -0,0 +1,45 @@
+#include <iostream>
+#include <algorithm>
+#include <cmath>
+#include <climits>
+
+using namespace std;
+
+typedef long long ll;
+
+int n, m, k, a[300002];
+ll ans, cache[300002];
+
+ll dp(int idx)
+{
+    ll& ret = cache[idx];
+    if(ret != LLONG_MIN) return ret;
+    if(idx == n - 1) return ret = a[idx] - k;
+
+    ll sum = 0;
+    for(int i = 0; i < n && i < m; i++)
+    {
+        sum += a[idx + i];
+        ret = max(ret, sum - k);
+    }
+
+    if(idx + m >= n) return ret;
+    else return ret = max(ret, sum - k + dp(idx + m));
+}
+
+int main()
+{
+    cin >> n >> m >> k;
+    for(int i = 0; i < n; i++) {
+        cin >> a[i];
+        cache[i] = LLONG_MIN;
+    }
+
+    for(int i = 0; i < n; i++) 
+    {
+        // cout << i << ' ' << dp(i) << '\n';
+        ans = max(ans, dp(i));
+    }
+
+    cout << ans << '\n';
+}

baekjoon/1396.cpp

@@ -102,5 +102,9 @@ int main()
         }
     }
 
-    for(int i = 0; i < q; i++) cout << Q[i].ans[0] << ' ' << Q[i].ans[1] << '\n';
+    for(int i = 0; i < q; i++) 
+    {
+        if(Q[i].ans[0] != 0) cout << Q[i].ans[0] << ' ' << Q[i].ans[1] << '\n';
+        else cout << -1 << '\n';
+    }
 }