Submission #43031

#	Time	Username	Problem	Language	Result	Execution time	Memory
43031		nonocut	Aliens (IOI16_aliens)	C++14	4 / 100	8 ms	620 KiB

aliens

#include "aliens.h"
#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define pii pair<ll,ll>
#define X first
#define Y second
const int maxn = 1e3 + 5;

struct line {
    ll m,c,val;
    line(ll _m = 0, ll _c = 0, ll _val = 0) {
        m = _m; c = _c; val = _val;
    }
};

int n,m,k,sz;
pii p[maxn];

pii dp[maxn];
line cht[maxn];

ll getpow(ll x) {
    return x*x;
}

double cut(int x, int y) {
    if(x==0 || y==0) return -2e16;
    return (double)(cht[y].c-cht[x].c)/(cht[x].m-cht[y].m);
}

void solve(ll cost) {
    int len = 0;
//    printf("solve %lld\n",cost);
    cht[++len] = line(-2*p[0].X,getpow(p[0].X),1);
    for(int x=0;x<sz;x++) {
        int pos = 1;
        for(int i=1;i<=len;i++) {
            if(cht[i].m*p[x].Y+cht[i].c < cht[pos].m*p[x].Y+cht[pos].c) pos = i;
        }
        dp[x] = {cht[pos].m*p[x].Y + cht[pos].c + getpow(p[x].Y) + cost, cht[pos].val};
        //update
        line t = line(-2*p[x+1].X, dp[x].X - getpow(max(0LL,p[x].Y-p[x+1].X)) + getpow(p[x+1].X), dp[x].Y+1);
        cht[++len] = t;
//        printf("dp %d = {%lld, %lld}\n",x,dp[x].X,dp[x].Y);
    }
}

bool cmp(pii x, pii y) {
    if(x.X!=y.X) return x.X<y.X;
    return x.Y>y.Y;
}

long long take_photos(int N, int M, int K, std::vector<int> R, std::vector<int> C) {
	n = N; m = M; k = K;
	//prep
	for(int i=0;i<n;i++) {
        p[i] = {R[i],C[i]};
        if(p[i].X>p[i].Y) swap(p[i].X,p[i].Y);
        p[i].Y++;
	}
	sort(p,p+n,cmp);
    ll cur = -1;
	for(int i=0;i<n;i++) {
        if(p[i].Y<=cur) continue;
        p[sz++] = p[i];
        cur = p[i].Y;
	}
	//solve
	ll l = 0, r = 1e13, mid, pos;
	ll ans;
	while(l<r) {
        mid = (l+r)/2;
        solve(mid);
        if(dp[sz-1].Y<=k) pos = mid, r = mid-1;
        else l = mid+1;
	}
	solve(pos);
    return dp[sz-1].X - pos*dp[sz-1].Y;
}

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:72:5: warning: unused variable 'ans' [-Wunused-variable]
  ll ans;
     ^
aliens.cpp:79:12: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
  solve(pos);
            ^

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