洛谷P8805
#include <iostream>
#include <istream>
#include <sstream>
#include <vector>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <algorithm>
#include <numeric>
#include <chrono>
#include <ctime>
#include <cmath>
#include <cctype>
#include <string>
#include <cstdio>
#include <iomanip>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <functional>
#include <iterator>
using namespace std;
//void rfIO()
//{
// FILE *stream1;
// freopen_s(&stream1,"in.txt", "r", stdin);
// freopen_s(&stream1,"out.txt", "w", stdout);
//}
inline int read(int& x) {
char ch = getchar();
int f = 1; x = 0;
while (ch > '9' || ch < '0') { if (ch == '-')f = -1; ch = getchar(); }
while (ch >= '0' && ch <= '9') { x = (x << 1) + (x << 3) + ch - '0'; ch = getchar(); }
return x * f;
}
//void ReadFile() {
// FILE* stream1;
// freopen_s(&stream1,"in.txt", "r", stdin);
// freopen_s(&stream1,"out.txt", "w", stdout);
//}
static auto speedup = []() {ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); return nullptr; }();
const int maxn = 1e5 + 7;
int f[maxn][21], v[maxn],n,m,dep[maxn],sum[maxn];
vector<int> g[maxn];
void dfs(int cur, int fa){
dep[cur] = dep[fa] + 1;
f[cur][0] = fa;
for (int i = 1; i <= 20; i++){
f[cur][i] = f[f[cur][i - 1]][i - 1];
}
for (auto &nx : g[cur]){
if (nx == fa)continue;
sum[nx] = sum[cur] + v[nx];
dfs(nx, cur);
}
}
int lca(int a, int b){
if (dep[a] > dep[b])swap(a, b);
for (int i = 20; i >= 0; i--){
if (dep[a] + (1 << i) <= dep[b]){
b = f[b][i];
}
}
if (a == b) return a;
for (int i = 20; i >= 0; i--){
if (f[a][i] != f[b][i]){
a = f[a][i];
b = f[b][i];
}
}
return f[a][0];
}
int main()
{
cin >> n >> m;
int a, b;
for (int i = 1; i < n; i++){
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
for (int i = 1; i <= n; i++){
sum[i] = v[i] = g[i].size();
}
dfs(1, 0);
for (int i = 0; i < m; i++){
cin >> a >> b;
int l = lca(a, b);
int ans = sum[a] + sum[b] - 2 * sum[l] + v[l];
cout << ans << endl;
}
return 0;
}
树上点差分
P3258
#include <iostream>
#include <istream>
#include <sstream>
#include <vector>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <algorithm>
#include <numeric>
#include <chrono>
#include <ctime>
#include <cmath>
#include <cctype>
#include <string>
#include <cstdio>
#include <iomanip>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <functional>
#include <iterator>
using namespace std;
inline int read(int& x) {
char ch = getchar();
int f = 1; x = 0;
while (ch > '9' || ch < '0') { if (ch == '-')f = -1; ch = getchar(); }
while (ch >= '0' && ch <= '9') { x = (x << 1) + (x << 3) + ch - '0'; ch = getchar(); }
return x * f;
}
//void ReadFile() {
// FILE* stream1;
// freopen_s(&stream1,"in.txt", "r", stdin);
// freopen_s(&stream1,"out.txt", "w", stdout);
//}
static auto speedup = []() {ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); return nullptr; }();
const int maxn = 3e5 + 7,LSP = 30;
int n,f[maxn][LSP + 1],dep[maxn], arr[maxn],ans[maxn];
vector<int> g[maxn];
void dfs(int cur, int fa) {
dep[cur] = dep[fa] + 1;
f[cur][0] = fa;
for (int i = 1; i <= LSP; i++) {
f[cur][i] = f[f[cur][i - 1]][i - 1];
}
for (auto& nx : g[cur]) {
if (nx == fa)continue;
dfs(nx, cur);
}
}
int lca(int a, int b) {
if (dep[a] > dep[b])swap(a, b);
for (int i = LSP; i >= 0; i--) {
if (dep[a] + (1 << i) <= dep[b]) {
b = f[b][i];
}
}
if (a == b)return a;
for (int i = LSP; i >= 0; i--) {
if (f[a][i] != f[b][i]) {
a = f[a][i];
b = f[b][i];
}
}
return f[a][0];
}
void getSum(int cur, int fa) {
for (auto& nx : g[cur]) {
if (nx == fa)continue;
getSum(nx, cur);
ans[cur] += ans[nx];
}
}
int main()
{
cin >> n;
for (int i = 1; i <= n; i++) cin >> arr[i];
int a, b,c;
for (int i = 1; i < n; i++) {
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
dfs(1, 0);
for (int i = 1; i < n; i++) {
a = arr[i], b = arr[i + 1], c = lca(a, b);
ans[f[c][0]]--;
ans[c]--;
ans[a]++;
ans[b]++;
}
getSum(1, 0);
for (int i = 2; i <= n; i++) {
ans[arr[i]]--;
}
for (int i = 1; i <= n; i++) {
cout << ans[i] << endl;
}
return 0;
}
树上边差分
P6869
#include <iostream>
#include <istream>
#include <sstream>
#include <vector>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <algorithm>
#include <numeric>
#include <chrono>
#include <ctime>
#include <cmath>
#include <cctype>
#include <string>
#include <cstdio>
#include <iomanip>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <functional>
#include <iterator>
using namespace std;
//void rfIO()
//{
// FILE *stream1;
// freopen_s(&stream1,"in.txt", "r", stdin);
// freopen_s(&stream1,"out.txt", "w", stdout);
//}
inline int read(int& x) {
char ch = getchar();
int f = 1; x = 0;
while (ch > '9' || ch < '0') { if (ch == '-')f = -1; ch = getchar(); }
while (ch >= '0' && ch <= '9') { x = (x << 1) + (x << 3) + ch - '0'; ch = getchar(); }
return x * f;
}
//void ReadFile() {
// FILE* stream1;
// freopen_s(&stream1,"in.txt", "r", stdin);
// freopen_s(&stream1,"out.txt", "w", stdout);
//}
static auto speedup = []() {ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); return nullptr; }();
const int maxn = 2e5 + 7, lg = 31;
int n, f[maxn][lg],val[maxn],dep[maxn];
long long int ans = 0;
struct Node{
long long int from, to, one, two;
Node(){ from = to = one = two = 0; }
Node(int a,int b,int c,int d) :from(a), to(b), one(c), two(d){}
};
vector<Node> g[maxn];
void dfs(int cur, int fa){
dep[cur] = dep[fa] + 1;
f[cur][0] = fa;
for (int i = 1; i < lg; i++){
f[cur][i] = f[f[cur][i - 1]][i - 1];
}
for (auto &p : g[cur]){
if (p.to == fa)continue;
dfs(p.to, cur);
}
}
int lca(int a, int b){
if (dep[a] > dep[b])swap(a, b);
for (int i = lg - 1; i >= 0; i--){
if (dep[a] + (1 << i) <= dep[b]){
b = f[b][i];
}
}
if (a == b) return a;
for (int i = lg - 1; i >= 0; i--){
if (f[a][i] != f[b][i]){
a = f[a][i];
b = f[b][i];
}
}
return f[a][0];
}
void slove(int x,int fa)
{
Node u;
for (auto &p : g[x]){
if (p.to == fa){
u = p;
}
else{
slove(p.to,x);
val[x] += val[p.to];
}
}
ans += min(u.one*val[x], u.two);
return;
}
int main()
{
cin >> n;
int a, b, c, d;
for (int i = 1; i < n; i++){
cin >> a >> b >> c >> d;
g[a].push_back({ a,b, c, d });
g[b].push_back({ b,a, c, d });
}
dfs(1, 0);
for (int i = 1; i < n; i++){
val[i]++; val[i + 1]++;
val[lca(i, i + 1)] -= 2;
}
slove(1,0);
cout << ans << endl;
return 0;
}