oj.uz

Submission #247701

# Submission time Handle Problem Language Result Execution time Memory
247701 2020-07-12T02:33:47 Z rqi Beads and wires (APIO14_beads) C++14
100 / 100
 305 ms 50916 KB 
#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef double db; 
typedef string str; 

typedef pair<int,int> pi;
typedef pair<ll,ll> pl; 
typedef pair<db,db> pd; 

typedef vector<int> vi; 
typedef vector<ll> vl; 
typedef vector<db> vd; 
typedef vector<str> vs; 
typedef vector<pi> vpi;
typedef vector<pl> vpl; 
typedef vector<pd> vpd; 

#define mp make_pair
#define f first
#define s second
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend() 
#define rsz resize
#define ins insert 
#define ft front() 
#define bk back()
#define pf push_front 
#define pb push_back
#define eb emplace_back 
#define lb lower_bound 
#define ub upper_bound 

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

const int MOD = 1e9+7; // 998244353;
const int MX = 2e5+5; 
const ll INF = 1e18; 
const ld PI = acos((ld)-1);
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; 
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 

template<class T> bool ckmin(T& a, const T& b) { 
    return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { 
    return a < b ? a = b, 1 : 0; } 
int pct(int x) { return __builtin_popcount(x); } 
int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
int cdiv(int a, int b) { return a/b+!(a<0||a%b == 0); } // division of a by b rounded up, assumes b > 0 
int fstTrue(function<bool(int)> f, int lo, int hi) {
    hi ++; assert(lo <= hi); // assuming f is increasing
    while (lo < hi) { // find first index such that f is true 
        int mid = (lo+hi)/2; 
        f(mid) ? hi = mid : lo = mid+1; 
    } 
    return lo;
}

// INPUT
template<class A> void re(complex<A>& c);
template<class A, class B> void re(pair<A,B>& p);
template<class A> void re(vector<A>& v);
template<class A, size_t SZ> void re(array<A,SZ>& a);

template<class T> void re(T& x) { cin >> x; }
void re(db& d) { str t; re(t); d = stod(t); }
void re(ld& d) { str t; re(t); d = stold(t); }
template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); }

template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; }
template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); }
template<class A> void re(vector<A>& x) { trav(a,x) re(a); }
template<class A, size_t SZ> void re(array<A,SZ>& x) { trav(a,x) re(a); }

// TO_STRING
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(bool b) { return b ? "true" : "false"; }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
template<class A> str ts(complex<A> c) { 
    stringstream ss; ss << c; return ss.str(); }
str ts(vector<bool> v) { 
    str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);
    res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) {
    str res = ""; F0R(i,SZ) res += char('0'+b[i]);
    return res; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> str ts(T v) { // containers with begin(), end()
    bool fst = 1; str res = "{";
    for (const auto& x: v) {
        if (!fst) res += ", ";
        fst = 0; res += ts(x);
    }
    res += "}"; return res;
}
template<class A, class B> str ts(pair<A,B> p) {
    return "("+ts(p.f)+", "+ts(p.s)+")"; }

// OUTPUT
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) { 
    pr(h); pr(t...); }
void ps() { pr("\n"); } // print w/ spaces
template<class H, class... T> void ps(const H& h, const T&... t) { 
    pr(h); if (sizeof...(t)) pr(" "); ps(t...); }

// DEBUG
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << ts(h); if (sizeof...(t)) cerr << ", ";
    DBG(t...); }
#ifdef LOCAL // compile with -DLOCAL
#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif

// FILE I/O
void setIn(string s) { freopen(s.c_str(),"r",stdin); }
void setOut(string s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { ios_base::sync_with_stdio(0); cin.tie(0); }
void setIO(string s = "") {
    unsyncIO();
    // cin.exceptions(cin.failbit); 
    // throws exception when do smth illegal
    // ex. try to read letter into int
    if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}

const int mx = 200005;

int n;
vector<pair<int, ll>> adj[mx]; // node, dist
pair<int, ll> par[mx];
vector<pair<int, ll>> children[mx];

ll dp[mx][2]; //filled everything up, 1 blue hanging from root
ll adp[mx][2];

void ndfs(int node, int prv = -1){
    for(auto u: adj[node]){
        if(u.f == prv) continue;
        par[u.f] = mp(node, u.s);
        children[node].pb(u);
        ndfs(u.f, node);
    }
    dp[node][0] = 0;

    for(auto u: adj[node]){
        if(u.f == prv) continue;
        dp[node][0]+=max(u.s+dp[u.f][1], dp[u.f][0]);
    }
    dp[node][1] = -INF;

    for(auto u: adj[node]){
        if(u.f == prv) continue;
        ckmax(dp[node][1], dp[node][0]-max(u.s+dp[u.f][1], dp[u.f][0])+u.s+dp[u.f][0]);
    }
    //dbg(node, dp[node][0]);
}



ll naivesolve(int R){
    //dbg(R);
    for(int i = 1; i <= n; i++){
        dp[i][0] = dp[i][1] = -INF;
    }
    ndfs(R);
    return dp[R][0]; 
}

void adfs(int node){
    //find answer for adp[children]
    ll dp0 = 0;
    for(auto u: children[node]){
        dp0+=max(dp[u.f][0], dp[u.f][1]+u.s);
    }
    if(node != 1) dp0+=max(adp[node][0], adp[node][1]+par[node].s);

    for(auto u: children[node]){
        adp[u.f][0] = dp0-max(dp[u.f][0], dp[u.f][1]+u.s);
    }

    vl vals;
    vl pre;
    vl suf;

    for(int i = 0; i < sz(children[node]); i++){
        pair<int, ll> u = children[node][i];
        vals.pb(u.s+dp[u.f][0]-max(dp[u.f][0], dp[u.f][1]+u.s));
    }

    pre = suf = vals;
    for(int i = 1; i < sz(pre); i++){
        ckmax(pre[i], pre[i-1]);
    }
    for(int i = sz(suf)-2; i >= 0; i--){
        ckmax(suf[i], suf[i+1]);
    }

    ll topval = -INF;
    if(node != 1){
        ckmax(topval, adp[node][0]+par[node].s-max(adp[node][0], adp[node][1]+par[node].s));
    }
    for(int i = 0; i < sz(children[node]); i++){
        pair<int, ll> u = children[node][i];
        ll bval = topval;
        if(i-1 >= 0) ckmax(bval, pre[i-1]);
        if(i+1 < sz(suf)) ckmax(bval, suf[i+1]);
        ckmax(adp[u.f][1], adp[u.f][0]+bval);
    }

    for(auto u: children[node]){
        adfs(u.f);
    }
}

ll smartsolve(int R){
    for(int i = 1; i <= n; i++){
        adp[i][0] = adp[i][1] = -INF;
    }
    adfs(R);
    ll ans = 0;
    for(int i = 1; i <= n; i++){
        if(i == R) continue;
        ckmax(ans, dp[i][0]+adp[i][0]);
        ckmax(ans, dp[i][0]+adp[i][1]+par[i].s);
    }
    return ans;
}


int main() {
    setIO();
    
    cin >> n;
    for(int i = 1; i <= n-1; i++){
        int a, b;
        ll c;
        cin >> a >> b >> c;
        adj[a].pb(mp(b, c));
        adj[b].pb(mp(a, c));
    }

    ll ans = 0;

    // for(int i = 1; i <= n; i++){
    //     //dbg(i, naivesolve(i));
    //     ckmax(ans, naivesolve(i));
    // }

    ckmax(ans, naivesolve(1));

    ckmax(ans, smartsolve(1));
    // for(int i = 1; i <= n; i++){
    //     dbg(i, adp[i][0], adp[i][1]);
    // }
    ps(ans);

    // you should actually read the stuff at the bottom
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?)
    * do smth instead of nothing and stay organized
    * WRITE STUFF DOWN
*/

Compilation message

beads.cpp: In function 'void setIn(std::__cxx11::string)':
beads.cpp:128:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setIn(string s) { freopen(s.c_str(),"r",stdin); }
                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
beads.cpp: In function 'void setOut(std::__cxx11::string)':
beads.cpp:129:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setOut(string s) { freopen(s.c_str(),"w",stdout); }
                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9728 KB Output is correct
2 Correct 5 ms 9728 KB Output is correct
3 Correct 5 ms 9728 KB Output is correct
4 Correct 6 ms 9728 KB Output is correct
5 Correct 5 ms 9728 KB Output is correct
6 Correct 5 ms 9728 KB Output is correct
7 Correct 5 ms 9728 KB Output is correct
8 Correct 5 ms 9728 KB Output is correct
9 Correct 5 ms 9728 KB Output is correct
10 Correct 5 ms 9728 KB Output is correct
11 Correct 5 ms 9728 KB Output is correct
12 Correct 5 ms 9728 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9728 KB Output is correct
2 Correct 5 ms 9728 KB Output is correct
3 Correct 5 ms 9728 KB Output is correct
4 Correct 6 ms 9728 KB Output is correct
5 Correct 5 ms 9728 KB Output is correct
6 Correct 5 ms 9728 KB Output is correct
7 Correct 5 ms 9728 KB Output is correct
8 Correct 5 ms 9728 KB Output is correct
9 Correct 5 ms 9728 KB Output is correct
10 Correct 5 ms 9728 KB Output is correct
11 Correct 5 ms 9728 KB Output is correct
12 Correct 5 ms 9728 KB Output is correct
13 Correct 5 ms 9728 KB Output is correct
14 Correct 5 ms 9728 KB Output is correct
15 Correct 5 ms 9728 KB Output is correct
16 Correct 6 ms 9728 KB Output is correct
17 Correct 6 ms 9728 KB Output is correct
18 Correct 6 ms 9728 KB Output is correct
19 Correct 5 ms 9728 KB Output is correct
20 Correct 6 ms 9856 KB Output is correct
21 Correct 5 ms 9728 KB Output is correct
22 Correct 5 ms 9856 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9728 KB Output is correct
2 Correct 5 ms 9728 KB Output is correct
3 Correct 5 ms 9728 KB Output is correct
4 Correct 6 ms 9728 KB Output is correct
5 Correct 5 ms 9728 KB Output is correct
6 Correct 5 ms 9728 KB Output is correct
7 Correct 5 ms 9728 KB Output is correct
8 Correct 5 ms 9728 KB Output is correct
9 Correct 5 ms 9728 KB Output is correct
10 Correct 5 ms 9728 KB Output is correct
11 Correct 5 ms 9728 KB Output is correct
12 Correct 5 ms 9728 KB Output is correct
13 Correct 5 ms 9728 KB Output is correct
14 Correct 5 ms 9728 KB Output is correct
15 Correct 5 ms 9728 KB Output is correct
16 Correct 6 ms 9728 KB Output is correct
17 Correct 6 ms 9728 KB Output is correct
18 Correct 6 ms 9728 KB Output is correct
19 Correct 5 ms 9728 KB Output is correct
20 Correct 6 ms 9856 KB Output is correct
21 Correct 5 ms 9728 KB Output is correct
22 Correct 5 ms 9856 KB Output is correct
23 Correct 9 ms 10496 KB Output is correct
24 Correct 8 ms 10496 KB Output is correct
25 Correct 9 ms 10496 KB Output is correct
26 Correct 13 ms 11136 KB Output is correct
27 Correct 13 ms 11136 KB Output is correct
28 Correct 11 ms 11260 KB Output is correct
29 Correct 11 ms 11264 KB Output is correct
30 Correct 10 ms 11264 KB Output is correct
31 Correct 13 ms 12288 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9728 KB Output is correct
2 Correct 5 ms 9728 KB Output is correct
3 Correct 5 ms 9728 KB Output is correct
4 Correct 6 ms 9728 KB Output is correct
5 Correct 5 ms 9728 KB Output is correct
6 Correct 5 ms 9728 KB Output is correct
7 Correct 5 ms 9728 KB Output is correct
8 Correct 5 ms 9728 KB Output is correct
9 Correct 5 ms 9728 KB Output is correct
10 Correct 5 ms 9728 KB Output is correct
11 Correct 5 ms 9728 KB Output is correct
12 Correct 5 ms 9728 KB Output is correct
13 Correct 5 ms 9728 KB Output is correct
14 Correct 5 ms 9728 KB Output is correct
15 Correct 5 ms 9728 KB Output is correct
16 Correct 6 ms 9728 KB Output is correct
17 Correct 6 ms 9728 KB Output is correct
18 Correct 6 ms 9728 KB Output is correct
19 Correct 5 ms 9728 KB Output is correct
20 Correct 6 ms 9856 KB Output is correct
21 Correct 5 ms 9728 KB Output is correct
22 Correct 5 ms 9856 KB Output is correct
23 Correct 9 ms 10496 KB Output is correct
24 Correct 8 ms 10496 KB Output is correct
25 Correct 9 ms 10496 KB Output is correct
26 Correct 13 ms 11136 KB Output is correct
27 Correct 13 ms 11136 KB Output is correct
28 Correct 11 ms 11260 KB Output is correct
29 Correct 11 ms 11264 KB Output is correct
30 Correct 10 ms 11264 KB Output is correct
31 Correct 13 ms 12288 KB Output is correct
32 Correct 47 ms 16760 KB Output is correct
33 Correct 55 ms 16760 KB Output is correct
34 Correct 50 ms 16760 KB Output is correct
35 Correct 280 ms 38144 KB Output is correct
36 Correct 305 ms 38136 KB Output is correct
37 Correct 272 ms 38012 KB Output is correct
38 Correct 180 ms 41948 KB Output is correct
39 Correct 146 ms 40648 KB Output is correct
40 Correct 160 ms 39968 KB Output is correct
41 Correct 237 ms 50916 KB Output is correct