#2606. 「NOIP2012」借教室

https://loj.ac/s/1314025

LibreOJ/2606/2606.cpp

@@ -0,0 +1,93 @@
+#include <bits/stdc++.h>
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+int n, m, d, s, t, a[1000005];
+
+// Segment Tree
+void pushup(int);
+void pushdown(int);
+void build(int, int, int);
+void modify(int, int, int, int);
+int query(int, int, int);
+
+int main() {
+    cin >> n >> m;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+    build(1, 1, n);
+    for (int i = 1; i <= m; i++) {
+        cin >> d >> s >> t;
+        if (query(1, s, t) < d) {
+            cout << -1 << endl
+                 << i << endl;
+            exit(0);
+        } else {
+            modify(1, s, t, -d);
+        }
+    }
+    cout << 0 << endl;
+    return 0;
+}
+
+// === Segment Tree ===
+
+struct node {
+    int l, r, m, d;
+
+    node()
+        : l(0), r(0), m(std::numeric_limits<int>::max()), d(0) {}
+    node(int _l, int _r)
+        : l(_l), r(_r), m(std::numeric_limits<int>::max()), d(0) {}
+} tr[1000005 << 1];
+
+void pushup(int u) {
+    tr[u].m = std::min(tr[u << 1].m, tr[u << 1 | 1].m);
+}
+
+void pushdown(int u) {
+    auto &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1];
+    left.m += root.d;
+    left.d += root.d;
+    right.m += root.d;
+    right.d += root.d;
+    root.d = 0;
+}
+
+void build(int u, int l, int r) {
+    tr[u] = node(l, r);
+    if (l == r) {
+        tr[u].m = a[l];
+        return;
+    }
+    int mid = l + r >> 1;
+    build(u << 1, l, mid);
+    build(u << 1 | 1, mid + 1, r);
+    pushup(u);
+}
+
+void modify(int u, int l, int r, int k) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        tr[u].m += k;
+        tr[u].d += k;
+        return;
+    }
+    int mid = tr[u].l + tr[u].r >> 1;
+    pushdown(u);
+    if (l <= mid) modify(u << 1, l, r, k);
+    if (r > mid) modify(u << 1 | 1, l, r, k);
+    pushup(u);
+}
+
+int query(int u, int l, int r) {
+    if (l <= tr[u].l && tr[u].r <= r) return tr[u].m;
+    int mid = tr[u].l + tr[u].r >> 1;
+    int min = std::numeric_limits<int>::max();
+    pushdown(u);
+    if (l <= mid) min = std::min(min, query(u << 1, l, r));
+    if (r > mid) min = std::min(min, query(u << 1 | 1, l, r));
+    return min;
+}