Submission #1268810

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268810		ilovewaguri	Power Plant (JOI20_power)	C++20	100 / 100	83 ms	26948 KiB

power

#include<bits/stdc++.h>
using namespace std;
#define NAME "FLORENTINO"
#define nl '\n'
#define allofa(x,sz) x,x+sz+1
#define allof(x) x.begin(),x.end()
#define allof1(x) x.begin()+1,x.end()
#define mset(x,val) memset(x,val,sizeof(x))
#define couf(x) cout << fixed << setprecision(x)
template<class T> T Abs(T &x) {return (x>=0 ? x : -x);};
template<class X,class Y> bool minimize(X &a, Y b){if(a>b) {a=b;return true;}return false;};
template<class X,class Y> bool maximize(X &a, Y b){if(a<b) {a=b;return true;}return false;};
typedef long long ll;
const ll mod = (long long)1e9+7;
const ll LINF = (long long)1e15;
const int INF = (int)1e9;
const int MAXN = (int)2e5+5;
vector<int> graph[MAXN];
int dp[MAXN][2];
char s[MAXN];
int n;

void ccps() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    if(fopen(NAME".inp","r")) {
        freopen(NAME".inp","r",stdin);
        freopen(NAME".out","w",stdout);
    }
}

void dfs(int u, int pre) {
    dp[u][1]=0;
    for (int v : graph[u]) {
        if(v^pre) {
            dfs(v,u);
            dp[u][1]+=dp[v][1];
        }
    }
    dp[u][1] = max(dp[u][1]-(s[u]=='1' ? 1 : 0),(s[u]=='1' ? 1 : 0));
    int opt1 = 0, opt2 = 0, opt3 = 0;
    for (int v : graph[u]) {
        if(v^pre) {
            maximize(opt1,dp[v][1]);
            maximize(opt3,dp[v][0]);
            opt2+=dp[v][1];
        }
    }
    dp[u][0]=max({(s[u]=='1' ? 1+opt1 : -INF),
                 opt2-(s[u]=='1' ? 1 : 0),
                 opt3,});
}

signed main() {
    ccps();
    cin >> n;
    for (int i = 1; i<n; i++) {
        int u,v; cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    for (int i = 1; i<=n; i++) {
        cin >> s[i];
    }
    dfs(1,0);
    cout << dp[1][0];
}

Compilation message (stderr)

power.cpp: In function 'void ccps()':
power.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen(NAME".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
power.cpp:28:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |         freopen(NAME".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 41 / 41
• Subtask 3: 53 / 53