ROJS 2017

Author: dolphingarlic

Romanian/ROJS 17-palindromic_tree.cpp

@@ -0,0 +1,15 @@
+/*
+ROJS 2017 Palidromic Tree
+- The pattern 001011001011... has at most 8 palindromes
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+    int n;
+    cin >> n;
+    cout << min(n, 8) << '\n';
+    for (int i = 0; i < n; i++) cout << "001011"[i % 6];
+    return 0;
+}

Romanian/ROJS 17-remove_update.cpp

@@ -0,0 +1,55 @@
+/*
+ROJS 2017 Remove Update
+- Apply all updates using a lazy segtree, and then try undo each one
+  and querying the range max
+- Complexity: O(Q log N)
+*/
+
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+struct Query { int a, b, v; } queries[100001];
+
+int n, q, segtree[400001], lazy[400001];
+
+void push_lazy(int node, int l, int r) {
+    segtree[node] += lazy[node];
+    if (l != r) {
+        lazy[node * 2] += lazy[node];
+        lazy[node * 2 + 1] += lazy[node];
+    }
+    lazy[node] = 0;
+}
+
+void update(int a, int b, int v, int node = 1, int l = 1, int r = n) {
+    push_lazy(node, l, r);
+    if (l > b || r < a) return;
+    if (l >= a && r <= b) {
+        lazy[node] = v;
+        push_lazy(node, l, r);
+    } else {
+        int mid = (l + r) / 2;
+        update(a, b, v, node * 2, l, mid);
+        update(a, b, v, node * 2 + 1, mid + 1, r);
+        segtree[node] = max(segtree[node * 2], segtree[node * 2 + 1]);
+    }
+}
+
+int main() {
+    ios_base::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> n >> q;
+    for (int i = 0; i < q; i++) {
+        cin >> queries[i].a >> queries[i].b >> queries[i].v;
+        update(queries[i].a, queries[i].b, queries[i].v);
+    }
+    int ans = INT_MAX;
+    for (int i = 0; i < q; i++) {
+        update(queries[i].a, queries[i].b, -queries[i].v);
+        ans = min(ans, segtree[1]);
+        update(queries[i].a, queries[i].b, queries[i].v);
+    }
+    cout << ans;
+    return 0;
+}