雅礼联考DAY01逃跑

Posted 2021-03-08 leiyuanze

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#include<cstdio>
using namespace std;

const int N = 30000;
const double INF = 1e8;
int n , l , a[N + 5] , b[N + 5] , c[N + 5] , q[N + 5] , head , tail , Mk , Mc;
double ans , f[N + 5] , w[N + 5];
struct tree{double max , tag;}t[(N << 2) + 5];

inline double max(double x , double y) {return x > y ? x : y;}

inline void build(int l , int r , int k)
{
    t[k] = (tree){0 , 0};
    if (l == r) 
    {
        t[k].max = f[l];
        return;
    }
    int mid = (l + r) >> 1;
    if (l <= mid) build(l , mid , k << 1);
    if (r > mid) build(mid + 1 , r , k << 1 | 1);
    t[k].max = max(t[k << 1].max , t[k << 1 | 1].max);
}

inline void pushdown(int k)
{
    if (!t[k].tag) return;
    t[k << 1].max += t[k].tag;
    t[k << 1 | 1].max += t[k].tag;
    t[k << 1].tag += t[k].tag;
    t[k << 1 | 1].tag += t[k].tag;
    t[k].tag = 0;
}

inline void update(int l , int r , int k , int x , double v)
{
    if (l == r && l == x)
    {
        t[k].max = v;
        return;
    }
    int mid = (l + r) >> 1;
    pushdown(k);
    if (x <= mid) update(l , mid , k << 1 , x , v);
    if (x > mid) update(mid + 1 , r , k << 1 | 1 , x , v);
    t[k].max = max(t[k << 1].max , t[k << 1 | 1].max);
}

inline void change(int l , int r , int k , int tl , int tr , double v)
{
    if (l >= tl && r <= tr)
    {
        t[k].tag += v;
        t[k].max += v;
        return;
    }
    int mid = (l + r) >> 1;
    pushdown(k);
    if (tl <= mid) change(l , mid , k << 1 , tl , tr , v);
    if (tr > mid) change(mid + 1 , r , k << 1 | 1 , tl , tr , v);
    t[k].max = max(t[k << 1].max , t[k << 1 | 1].max);
}

inline double query(int l , int r , int k , int tl , int tr)
{
    if (l >= tl && r <= tr) return t[k].max;
    int mid = (l + r) >> 1;
    double res = -INF;
    pushdown(k);
    if (tl <= mid) res = max(res , query(l , mid , k << 1 , tl , tr));
    if (tr > mid) res = max(res , query(mid + 1 , r , k << 1 | 1 , tl , tr));
    return res;
}

inline bool check(double m)
{
    for(register int i = 1; i <= n; i++) w[i] = a[i] - b[i] * m , f[i] = -INF;
    f[0] = 0;
    build(0 , n , 1);
    q[head = tail = 1] = 0;
    for(register int i = 1; i <= n; i++)
    {
        while (head < tail && c[i] >= c[q[tail]])
        {
            change(0 , n , 1 , q[tail - 1] , q[tail] - 1 , -w[q[tail]]);
            tail--;
        }
        q[++tail] = i;  
        change(0 , n , 1 , q[tail - 1] , q[tail] - 1 , w[q[tail]]);
        f[i] = query(0 , n , 1 , i - l > 0 ? i - l : 0 , i - 1);
        update(0 , n , 1 , i , f[i]);
    }
    return f[n] >= 0;
}

int main()
{
//  freopen("逃跑.in" , "r" , stdin);
    scanf("%d%d" , &n , &l);
    for(register int i = 1; i <= n; i++) scanf("%d%d%d" , &a[i] , &b[i] , &c[i]);
    c[0] = INF;
    double l = 0 , r = 1e6 , mid;
    for(register int i = 1; i <= 60; i++)
    {
        mid = (l + r) * 0.5;
        if (check(mid)) l = mid , ans = mid;
        else r = mid;
    }
    
    if (ans == 0) 
    {
        puts("0.000000000e+000");   
        return 0;
    }
    Mk = 0 , Mc;
    if (ans < 1)
    {   
        while (ans < 1) ans *= 10 , Mk++;
        printf("%.9lfe-" , ans);
        if (Mk == 0) Mc = 3;
        else if (Mk < 10) Mc = 2;
        else if (Mk < 100) Mc = 1;
        else Mc = 0;
        while (Mc--) putchar('0');
        if (Mk > 0) printf("%d" , Mk);
        return 0;
    } 
    while (ans >= 10) ans /= 10 , Mk++;
    printf("%.9lfe+" , ans);
    if (Mk == 0) Mc = 3;
    else if (Mk < 10) Mc = 2;
    else if (Mk < 100) Mc = 1;
    else Mc = 0;
    while (Mc--) putchar('0');
    if (Mk > 0) printf("%d" , Mk);
}