2017 ICPC Asia Xian Onsite H. Arrangement for Contests #线段树#

Portal

很容易想到贪心+线段树查询维护

UVa上这题是假数据 O(nk)暴力都能0ms AC...

此外输入可能是空文件 坑！！！

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

typedef long long ll;
const int maxn = 1e5 + 10;
struct node { int l, r, minv, minp, lz; } tree[maxn << 2];
struct Min
{
    int v, p;
    Min(int v, int p) { this->v = v; this->p = p; }
    bool operator < (const Min& x) const { return v == x.v ? p > x.p : v < x.v;  }
};

inline const int read()
{
    int x = 0, f = 1; char ch = getchar();
    while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); }
    while (ch >= '0' && ch <= '9') { x = (x << 3) + (x << 1) + ch - '0'; ch = getchar(); }
    return x * f;
}

inline int ls(int id) { return id << 1; }

inline int rs(int id) { return id << 1 | 1; }

void push_up(int id)
{
    if (tree[rs(id)].minv <= tree[ls(id)].minv)
    {
        tree[id].minv = tree[rs(id)].minv;
        tree[id].minp = tree[rs(id)].minp;
    }
    else
    {
        tree[id].minv = tree[ls(id)].minv;
        tree[id].minp = tree[ls(id)].minp;
    }
}

void push_down(int id)
{
    if (tree[id].lz)
    {
        tree[ls(id)].minv -= tree[id].lz;
        tree[ls(id)].lz += tree[id].lz;
        tree[rs(id)].minv -= tree[id].lz;
        tree[rs(id)].lz += tree[id].lz;
        tree[id].lz = 0;
    }
}

void build(int id, int l, int r)
{
    tree[id].l = l;
    tree[id].r = r;
    tree[id].lz = 0;
    tree[id].minv = 0x3f3f3f3f;
    if (l == r)
    {
        tree[id].minv = read();
        tree[id].minp = l;
        return;
    }
    int mid = (l + r) >> 1;
    build(ls(id), l, mid);
    build(rs(id), mid + 1, r);
    push_up(id);
}

Min query(int id, int l, int r)
{
    if (tree[id].l == l && tree[id].r == r) return Min(tree[id].minv, tree[id].minp);
    push_down(id);
    int mid = (tree[id].l + tree[id].r) >> 1;
    if (r <= mid) return query(ls(id), l, r);
    if (l > mid) return query(rs(id), l, r);
    return min(query(ls(id), l, mid), query(rs(id), mid + 1, r));
}

void update(int id, int l, int r, int sub)
{
    if (tree[id].l == l && tree[id].r == r)
    {
        tree[id].minv -= sub;
        tree[id].lz += sub;
        return;
    }
    push_down(id);
    int mid = (tree[id].l + tree[id].r) >> 1;
    if (r <= mid) update(ls(id), l, r, sub);
    else if (l > mid) update(rs(id), l, r, sub);
    else
    {
        update(ls(id), l, mid, sub);
        update(rs(id), mid + 1, r, sub);
    }
    push_up(id);
}

int main()
{
    int t = 0;
    scanf("%d", &t);
    while (t--)
    {
        int n = read(), k = read();
        build(1, 1, n);
        ll res = 0;
        for (int i = 1; i <= n - k + 1; )
        {
            Min m = query(1, i, i + k - 1);
            int minv = m.v, minp = m.p;
            if (minv > 0)
            {
                res += minv;
                update(1, i, i + k - 1, minv);
            }
            i = minp + 1;
        }
        printf("%lld\n", res);
    }
    return 0;
}