제출 #224757

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
224757		urd05	수열 (APIO14_sequence)	C++14	0 / 100	75 ms	131076 KiB

sequence

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

long long dp[100001][201];
long long psum[100001];
int n;

struct Line {
    long long a,b;
};

struct Fraction {
    long long up,down;
};

Fraction cross(Line one,Line two) {
    if (one.a<two.a) {
        swap(one,two);
    }
    return {two.b-one.b,one.a-two.a};
}

bool cmp(Fraction one,Fraction two) {
    return one.up*two.down<one.down*two.up;
}

void getans(int k,int l,int r,int al,int ar) {
    if (l>r) {
        return;
    }
    int mid=(l+r)/2;
    long long maxi=-1e18;
    int opt=-1;
    for(int i=al;i<=min(mid-1,ar);i++) {
        long long val=dp[i][k-1]+psum[i+1]*(psum[mid+1]-psum[i+1]);
        if (maxi<val) {
            maxi=val;
            opt=i;
        }
    }
    dp[mid][k]=maxi;
    getans(k,l,mid-1,al,opt);
    getans(k,mid+1,r,opt,ar);
}

Line arr[100001];
int sz;

void insert(Line l) {
    if (sz>=1&&arr[sz-1].a==l.a) {
        if (l.b>arr[sz-1].b) {
            arr[sz-1]=l;
        }
        return;
    }
    while (sz>1) {
        Fraction before=cross(arr[sz-2],arr[sz-1]);
        Fraction now=cross(arr[sz-1],l);
        if (cmp(before,now)) {
            break;
        }
        sz--;
    }
    arr[sz++]=l;
}

int main(void) {
    int k;
    scanf("%d %d\n",&n,&k);
    for(int i=0;i<n;i++) {
        long long x;
        scanf("%lld",&x);
        psum[i+1]=psum[i]+x;
    }
    for(int i=0;i<n;i++) {
        for(int j=0;j<=k;j++) {
            dp[i][j]=-1e18;
        }
    }
    for(int i=0;i<n;i++) {
        dp[i][0]=0;
    }
    int ind=0;
    for(int i=1;i<=k;i++) {
        sz=0;
        ind=0;
        insert({0,-1000000000000000000LL});
        for(int j=0;j<n;j++) {
            while (ind+1<sz&&cmp(cross(arr[ind],arr[ind+1]),{psum[j+1],1})) {
                ind++;
            }
            long long val;
            if (ind>=sz) {
                val=-1e18;
            }
            else {
                val=arr[ind].a*psum[j+1]+arr[ind].b;
            }
            dp[j][i]=val;
            insert({psum[j+1],-psum[j+1]*psum[j+1]+dp[j][i-1]});
        }
    }
    printf("%lld\n",dp[n-1][k]);
    int now=n-1;
    vector<int> ret;
    for(int i=k;i>=1;i--) {
        for(int j=now-1;j>=0;j--) {
            if (dp[j][i-1]+psum[j+1]*(psum[now+1]-psum[j+1])==dp[now][i]) {
                ret.push_back(j);
                now=j;
                break;
            }
        }
    }
    reverse(ret.begin(),ret.end());
    for(int i=0;i<k;i++) {
        printf("%d ",ret[i]+1);
    }
}

컴파일 시 표준 에러 (stderr) 메시지

sequence.cpp: In function 'int main()':
sequence.cpp:69:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d\n",&n,&k);
     ~~~~~^~~~~~~~~~~~~~~~~
sequence.cpp:72:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld",&x);
         ~~~~~^~~~~~~~~~~

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