Submission #439727

#	Time	Username	Problem	Language	Result	Execution time	Memory
439727		vulpes2	Handcrafted Gift (IOI20_gift)	C++17	100 / 100	794 ms	95356 KiB

gift

//#include <atcoder/maxflow.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
 

#include <iostream>
#include <map>
#include <list>
#include <set>
#include <algorithm>
#include <vector>
#include <string>
#include <functional>
#include <queue>
#include <deque>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <cmath>
#include <iterator>
#include <random>
#include <chrono>
#include <complex>
#include <bitset>
#include <fstream>
 
 
#define forr(i,start,count) for (int i = (start); i < (start)+(count); ++i)
#define set_map_includes(set, elt) (set.find((elt)) != set.end())
#define readint(i) int i; cin >> i
#define readll(i) ll i; cin >> i
#define readdouble(i) double i; cin >> i
#define readstring(s) string s; cin >> s

typedef long long ll;

 
//using namespace __gnu_pbds;
//using namespace atcoder;
using namespace std;

//const ll modd = (1000LL * 1000LL * 1000LL + 7LL);
const ll modd = 998244353;


class UnionFind {
    public:
      vector<int> parent;
      vector<int> size;
//      size[i] = number of nodes in tree rooted at i
// Note: not necessarily correct if i is not a root node
      map<int,set<int>> elts;

    UnionFind(int n) : parent(n), size(n) {
        forr(i,0,n) {
            parent[i] = i; size[i] = 1;
            elts[i].insert(i);
        }
    } 

    int Find(int p) {
        int root = p;
        while (root != parent[root]) {  root = parent[root]; }
        while (p != root) {
            int newp = parent[p];
            parent[p] = root;
            p = newp;
        }
        return root;
    }

    void Union(int p, int q) {
        int rootP = Find(p);
        int rootQ = Find(q);
        if (rootP == rootQ) return;

        if (size[rootP] < size[rootQ]) {
            parent[rootP] = rootQ;
            size[rootQ] += size[rootP];
            for(auto x : elts[rootP]) { elts[rootQ].insert(x); }
            elts.erase(rootP);
        }
        else {
            parent[rootQ] = rootP;
            size[rootP] += size[rootQ];
            for(auto x : elts[rootQ]) { elts[rootP].insert(x); }
            elts.erase(rootQ);
        }
    }

};


int construct(int n, int r, std::vector<int> a, std::vector<int> b,  std::vector<int> x);
void craft(std::string &s);

int construct(int n, int r, std::vector<int> a, std::vector<int> b, std::vector<int> x) {
    UnionFind uf(n);
    forr(i,0,r) {
        if (x[i]==2) { continue; }
        int l = a[i], r = b[i];
        int curr = l;
        while (curr < r) {
            uf.Union(curr, curr+1);
            curr = *prev(uf.elts[uf.Find(curr)].end())-1;
            ++curr;
        }
    }
    bool problem = false;
    forr(i,0,r) {
        if (x[i]==1) { continue; }
        int l = a[i], r = b[i];
        problem |= (uf.Find(l)==uf.Find(r));
    }
    if (problem) {
        return 0;
    }
    std::string s(n, 'R');
    char c = 'R';
    for(auto x : uf.elts) {
        for(auto y : x.second) {
            s[y] = c;
        }
        c = (c=='R' ? 'B' : 'R');
    }
    craft(s);
    return 1;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 20 / 20
• Subtask 4: 25 / 25
• Subtask 5: 30 / 30