Submission #522502

#	Time	Username	Problem	Language	Result	Execution time	Memory
522502		byunjaewoo	Aliens (IOI16_aliens)	C++17	12 / 100	1 ms	332 KiB

aliens

#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;
using ll=long long;
using ld=long double;
using pp=pair<ll, ll>;

const int Nmax=100010;
ll N, NN, M, K, DP[Nmax], C[Nmax];
pp A[Nmax], B[Nmax];
struct line {
    ll a, b;
    int idx;
    ll f(ll x) {return a*x+b;}
    ld cross(line r) {return (b-r.b)/(r.a-a);}
}L[Nmax];

void Dynamic(ll v) {
    int fr=1, re=0;
    fill(C+1, C+N+1, 0);
    for(int i=1; i<=N; i++) {
        line tmp={-2*A[i].x, DP[i-1]+A[i].x*A[i].x-2*A[i].x, i};
        while(fr<re && L[re-1].cross(tmp)<L[re-1].cross(L[re])) re--;
        L[++re]=tmp;
        while(fr<re && L[fr].cross(L[fr+1])<A[i].y) fr++;
        DP[i]=L[fr].f(A[i].y)+A[i].y*A[i].y+v+2*A[i].y+1;
        C[i]=C[L[fr].idx-1]+1;
    }
}

ll take_photos(int n, int m, int k, std::vector<int> r, std::vector<int> c) {
    NN=n, M=m, K=k;
    for(int i=1; i<=NN; i++) {
        B[i].x=min(r[i-1], c[i-1]), B[i].y=max(r[i-1], c[i-1]);
    }
    sort(B+1, B+NN+1, [](pp a, pp b) {
        return a.x!=b.x?a.x<b.x:a.y>b.y;
    });
    for(int i=1; i<=NN; i++) {
        if(N && B[i].y<=A[N].y) continue;
        while(N && A[N].y>=B[i].y) N--;
        A[++N]=B[i];
    }
    K=min(K, N);
    {
    ll l=0, r=N+1, lv, rv;
    for(ll s=0, e=M*M; s<=e;) {
        ll mid=(s+e)/2;
        Dynamic(mid);
        if(C[N]==K) return DP[N]-mid*C[N];
        else if(C[N]>K) {
            s=mid+1;
            if(r>C[N]) r=C[N], rv=DP[N]-mid*C[N];
        }
        else {
            e=mid-1;
            if(l<C[N]) l=C[N], lv=DP[N]-mid*C[N];
        }
    }
    return rv+(lv-rv)/(r-l)*(r-K);
    }
}

Compilation message (stderr)

aliens.cpp: In function 'll take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:61:33: warning: 'rv' may be used uninitialized in this function [-Wmaybe-uninitialized]
   61 |     return rv+(lv-rv)/(r-l)*(r-K);
      |                                 ^
aliens.cpp:61:18: warning: 'lv' may be used uninitialized in this function [-Wmaybe-uninitialized]
   61 |     return rv+(lv-rv)/(r-l)*(r-K);
      |               ~~~^~~~

• Subtask 1: 0 / 4
• Subtask 2: 12 / 12
• Subtask 3: 0 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 40