Submission #522246

#	Time	Username	Problem	Language	Result	Execution time	Memory
522246		sudheerays123	Watching (JOI13_watching)	C++17	50 / 100	1038 ms	15252 KiB

watching

#include <bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define ll int
#define tc ll test;cin >> test;while(test--)
#define vi vector<ll>
#define pll pair<ll,ll>
#define pb push_back
#define mp make_pair
#define INF 1e18
#define MOD 1000000007
#define ff first
#define ss second
#define in >>
#define out <<
#define space << " " <<
#define spacef << " "
#define fo(i,a,b) for(ll i = a; i <= b; i++)
#define nextline out "\n"
#define print(x) for(auto i : x ) cout out i spacef
#define mmax(x,i) x = max(x,i)
#define mmin(x,i) x = min(x,i)
#define N 2005

ll n;
vi a(N);

bool check(ll w , ll p , ll q){
    
    ll dp[n+5][p+5];

    // dp[i][j] = minimum number of large cameras needed till i if we use j small cameras

    // base case :

    fo(i,0,p) dp[0][i] = 0;
    fo(i,1,n){
        
        auto it = lower_bound(a.begin()+1,a.begin()+n+1,a[i]-2*w+1);
        ll pos = it-a.begin();

        dp[i][0] = dp[pos-1][0]+1;
    }

    // recursive relation :

    fo(i,1,n){
        fo(j,1,p){

            auto low1 = lower_bound(a.begin()+1,a.begin()+n+1,a[i]-w+1);
            ll pos1 = low1-a.begin();

            dp[i][j] = dp[pos1-1][j-1];

            auto low2 = lower_bound(a.begin()+1,a.begin()+n+1,a[i]-2*w+1);
            ll pos2 = low2-a.begin();

            mmin(dp[i][j],dp[pos2-1][j]+1);
        }
    }

    return dp[n][p] <= q;
}

int main() {
    
    fast;

    ll p,q;
    cin in n in p in q;

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

    fo(i,1,n) cin in a[i];
    sort(a.begin()+1,a.begin()+n+1);

    ll low = 1 , high = a[n];
    ll ans;

    while(low <= high){
        ll mid = (low+high)/2;

        if(check(mid,p,q)){
            ans = mid;
            high = mid-1;
        }
        else{
            low = mid+1;
       }
    }

    cout out ans;

    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:95:14: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   95 |     cout out ans;
      |              ^~~

• Subtask 1: 50 / 50
• Subtask 2: 0 / 50