Tree Journey
猜结论
#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e5 + 5;
int n, k, ans, dep[N];
vector<int> g[N];
void dfs(int u, int f) {
dep[u] = dep[f] + 1;
for (auto v : g[u]) {
if (v == f) {
continue;
}
dfs(v, u);
}
if (dep[u] - 1 <= k) {
ans = max(ans, min(n, dep[u] + (k - dep[u] + 1) / 2));
}
}
signed main() {
cin >> n >> k;
for (int i = 1, u, v; i < n; i++) {
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
dfs(1, 0);
cout << ans;
return 0;
}
Infinity Card Decks
我们显然只用考虑 \(a[i] > b[i]\) 的数对,假设现在考虑第 \(j\) 张牌是否能打断无限牌组.
设\(suma, sumb\)表示\(a[i],b[i]\)之和.
\(M - (suma - sumb) - b[j] < 0\)
\(M - (suma - sumb) - a[j] < 0\)
我们显然会发现这个是单调的,所以就可以了
#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e6 + 5, INF = 1e18;
int n, m, sum[N], suma[N], sumb[N], p[N], a[N], b[N], res[N], ans, pos[N], pos1[N];
int tr[3][N * 4];
void Merge(int i) {
tr[1][i] = tr[1][i * 2] + tr[1][i * 2 + 1];
tr[2][i] = max(tr[2][i * 2], tr[2][i * 2 + 1]);
}
void build(int i, int l, int r) {
if (l == r) {
tr[1][i] = 0;
if (a[l] > b[l]) {
tr[2][i] = b[l];
}
else {
tr[2][i] = a[l];
}
return ;
}
int mid = (l + r) >> 1;
build(i * 2, l, mid);
build(i * 2 + 1, mid + 1, r);
Merge(i);
}
int query_max(int i, int l, int r, int x, int y) {
if (x > y) {
return -INF;
}
if (l > y || r < x) {
return -INF;
}
if (l >= x && r <= y) {
return tr[2][i];
}
int mid = (l + r) >> 1;
return max(query_max(i * 2, l, mid, x, y), query_max(i * 2 + 1, mid + 1, r, x, y));
}
int query_sum(int i, int l, int r, int x, int y) {
if (x > y) {
return 0;
}
if (l > y || r < x) {
return 0;
}
if (l >= x && r <= y) {
return tr[1][i];
}
int mid = (l + r) >> 1;
return query_sum(i * 2, l, mid, x, y) + query_sum(i * 2 + 1, mid + 1, r, x, y);
}
void modify(int i, int l, int r, int p, int x) {
if (l == r) {
tr[1][i] += x;
return ;
}
int mid = (l + r) >> 1;
if (mid >= p) modify(i * 2, l, mid, p, x);
else modify(i * 2 + 1, mid + 1, r, p, x);
Merge(i);
}
signed main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
for (int i = 1; i <= n; i++) {
cin >> b[i];
}
build(1, 1, n);
for (int i = 1; i <= n; i++) {
sum[i] = sum[i - 1] + (a[i] - b[i]);
suma[i] = suma[i - 1];
sumb[i] = sumb[i - 1];
if (a[i] > b[i]) {
suma[i] += a[i];
sumb[i] += b[i];
}
p[i] = sum[i];
}
sort(p + 1, p + n + 1);
for (int i = 0; i <= n; i++) {
pos[i] = lower_bound(p + 1, p + n + 1, sum[i]) - p;
pos1[i] = upper_bound(p + 1, p + n + 1, sum[i]) - p;
}
for (int i = 1, j = 1; i <= n; i++) {
while (j <= n && m - ((suma[j] - suma[i - 1]) - (sumb[j] - sumb[i - 1])) - query_max(1, 1, n, i, j) >= 0) {
j++;
}
res[i] = j;
}
for (int i = 1, j = 1; i <= n; i++) {
while (j < res[i]) {
modify(1, 1, n, pos[j], 1);
j++;
}
ans += (n - res[i] + 1);
ans += query_sum(1, 1, n, pos1[i - 1], n);
if (i <= res[i]) {
modify(1, 1, n, pos[i], -1);
}
}
cout << (n * (n + 1) / 2) - ans;
return 0;
}
标签:return,int,sum,tr,mid,query,20240929
From: https://www.cnblogs.com/libohan/p/18440592