Submission #1146037

#	Time	Username	Problem	Language	Result	Execution time	Memory
1146037		agrim_09	Watching (JOI13_watching)	C++20	100 / 100	691 ms	15880 KiB

watching

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define endl '\n';
#define fastio ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define py cout << "YES" << endl;
#define pn cout << "NO" << endl;
#define pb push_back
#define int long long
typedef long double lld;
#define double lld
typedef long long ll;
typedef unsigned long long ull;
const ll inf = 1e18;
const ll mod = 1e9+7;
const int N = 2e5;
vector<int>primes = {2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97};

// Check for queue, priorioty_queue, stack, ordered_set solutions
// stack => LIFO (whatever goes in last comes out last)
// queue => FIFO (whatever goes in first comes out first)
// priority_queue => Dynamic queries of minimum/maximum
// ordered_set => set in vector form
//[order_of_key(k) gives number of elements less than k, while find_by_order(i) gives i^th element]

// To comment multiple lines : ctrl + /
// To find and replace : ctrl+H

void judge(){
    srand(time(NULL));
    #ifndef ONLINE_JUDGE
    freopen("1.txt","r",stdin);
    freopen("2.txt","w",stdout);
    freopen("Error.txt", "w", stderr);
    #define debug(x...) cerr << #x <<" = "; _print(x); cerr << endl;
    #else
    #define debug(x...)
    #endif
}

void usaco(string s) {
    freopen((s + ".in").c_str(),"r",stdin);
    freopen((s + ".out").c_str(),"w",stdout);
}

signed main(){
    fastio; //judge();
    int n,p,q; cin >> n >> p >> q;
    vector<int>a(n);
    for(auto &x : a) cin >> x;
    sort(a.begin(),a.end());

    if((p+q)>=n){
        cout << 1; return 0;
    }

    auto f1 = [&](int x){
        vector<vector<int>>dp(n,vector<int>(p+1));
        
        for(int i = n-1;i>=0;i--){
            auto it = upper_bound(a.begin(),a.end(),a[i]+2*x-1);
            if(it==a.end()){
                for(int j = 0;j<=p;j++){
                    dp[i][j] = 1;
                }
            }
            else{
                for(int j = 0;j<=p;j++){
                    dp[i][j] = 1 + dp[it-a.begin()][j];
                }
            }

            for(int j = 1;j<=p;j++){
                auto it = upper_bound(a.begin(),a.end(),a[i]+x-1);
                if(it==a.end()){
                    dp[i][j] = 0;
                }
                else{
                    dp[i][j] = min(dp[i][j],dp[it-a.begin()][j-1]);
                }
            }
        }
        return (dp[0][p] <= q);
    };
    auto f2 = [&](int x){
        vector<vector<int>>dp(n,vector<int>(q+1));
        
        for(int i = n-1;i>=0;i--){
            auto it = upper_bound(a.begin(),a.end(),a[i]+x-1);
            if(it==a.end()){
                for(int j = 0;j<=q;j++){
                    dp[i][j] = 1;
                }
            }
            else{
                for(int j = 0;j<=q;j++){
                    dp[i][j] = 1 + dp[it-a.begin()][j];
                }
            }

            for(int j = 1;j<=q;j++){
                auto it = upper_bound(a.begin(),a.end(),a[i]+2*x-1);
                if(it==a.end()){
                    dp[i][j] = 0;
                }
                else{
                    dp[i][j] = min(dp[i][j],dp[it-a.begin()][j-1]);
                }
            }
        }
        return (dp[0][q] <= p);
    };
    int low = 1, high = 1e9, ans = inf;
    while(low<=high){
        int mid = (low+high)/2;
        if(p<=q){
            if(f1(mid)){
                ans = mid, high = mid-1;
            }
            else{
                low = mid+1;
            }
        }
        else{
            if(f2(mid)){
                ans = mid, high = mid-1;
            }
            else{
                low = mid+1;
            }
        }
    }
    cout << ans;
}

Compilation message (stderr)

watching.cpp: In function 'void judge()':
watching.cpp:37:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |     freopen("1.txt","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~
watching.cpp:38:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |     freopen("2.txt","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~
watching.cpp:39:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |     freopen("Error.txt", "w", stderr);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp: In function 'void usaco(std::string)':
watching.cpp:47:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |     freopen((s + ".in").c_str(),"r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:48:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |     freopen((s + ".out").c_str(),"w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50