B - Stone Age Problem

https://codeforces.com/contest/1679/submission/157152636

Codeforces/1679/B/B.cpp

@@ -0,0 +1,90 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+struct node {
+    int l, r;
+    long long s, d;
+
+    node() {
+        l = r = s = d = 0;
+    }
+    node(int _l, int _r) {
+        l = _l;
+        r = _r;
+        s = d = 0;
+    }
+} tr[1000005 << 2];
+
+int n, q, op, l, r;
+long long x, a[1000005];
+
+void pushup(int u) {
+    tr[u].s = tr[u << 1].s + tr[u << 1 | 1].s;
+}
+
+void pushdown(int u) {
+    if (!tr[u].d) return;
+    tr[u << 1].d = tr[u].d;
+    tr[u << 1].s = (tr[u << 1].r - tr[u << 1].l + 1) * tr[u].d;
+    tr[u << 1 | 1].d = tr[u].d;
+    tr[u << 1 | 1].s = (tr[u << 1 | 1].r - tr[u << 1 | 1].l + 1) * tr[u].d;
+    tr[u].d = 0;
+}
+
+void build(int u, int l, int r) {
+    tr[u] = node(l, r);
+    if (l == r) {
+        tr[u].s = 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, long long d) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        tr[u].d = d;
+        tr[u].s = (tr[u].r - tr[u].l + 1) * d;
+        return;
+    }
+    int mid = tr[u].l + tr[u].r >> 1;
+    pushdown(u);
+    if (l <= mid) modify(u << 1, l, r, d);
+    if (r > mid) modify(u << 1 | 1, l, r, d);
+    pushup(u);
+}
+
+long long query(int u, int l, int r) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        return tr[u].s;
+    }
+    int mid = tr[u].l + tr[u].r >> 1;
+    long long s = 0;
+    pushdown(u);
+    if (l <= mid) s += query(u << 1, l, r);
+    if (r > mid) s += query(u << 1 | 1, l, r);
+    return s;
+}
+
+int main() {
+    scanf("%d%d", &n, &q);
+    for (int i = 1; i <= n; i++) {
+        scanf("%lld", a + i);
+    }
+    build(1, 1, n);
+    for (int i = 0; i < q; i++) {
+        scanf("%d", &op);
+        if (op == 1) {
+            scanf("%d%lld", &l, &x);
+            modify(1, l, l, x);
+        } else if (op == 2) {
+            scanf("%lld", &x);
+            modify(1, 1, n, x);
+        }
+        printf("%lld\n", query(1, 1, n));
+    }
+    return 0;
+}