洛谷1070 道路游戏

原题链接

太菜了，只会\(O(n^3)\)暴力\(DP\)，最后看大佬的博客看了好久也是一知半解。。
大佬博客传送门

#include<cstdio>
#include<cstring>
using namespace std;
const int N = 1010;
struct dd{
    int l, r, v[N], id[N];
};
dd q[N];
int f[N], mo[N][N], S[N][N], co[N], n;
inline int re()
{
    int x = 0;
    char c = getchar();
    bool p = 0;
    for (; c < '0' || c > '9'; c = getchar())
        p |= c == '-';
    for (; c >= '0' && c <= '9'; c = getchar())
        x = x * 10 + c - '0';
    return p ? -x : x;
}
inline int maxn(int x, int y)
{
    return x > y ? x : y;
}
inline int pos(int x, int y)
{
    return ((x - y) % n + n) % n;
}
int main()
{
    int i, j, k, m, p, o;
    n = re();
    m = re();
    p = re();
    for (i = 0; i < n; i++)
        for (j = 1; j <= m; j++)
            S[i][j] = re();
    for (i = 0; i < n; i++)
    {
        co[i] = re();
        j = (i + 1) ^ n ? i + 1 : 0;
        q[j].l = 1;
        q[j].v[++q[j].r] = -co[i];
    }
    for (j = 2; j <= m; j++)
        for (i = 0; i < n; i++)
            S[i][j] += S[(i + n - 1) % n][j - 1];
    memset(f, 250, sizeof(f));
    f[0] = 0;
    for (i = 1; i <= m; i++)
    {
        for (j = 0; j < n; j++)
        {
            k = pos(j, i - 1);
            f[i] = maxn(f[i], q[k].v[q[k].l] + S[pos(j, 1)][i]);
        }
        for (j = 0; j < n; j++)
        {
            k = pos(j, i - 1);
            for (; q[k].l <= q[k].r && q[k].id[q[k].l] < i - p + 1; q[k].l++);
            o = f[i] - S[pos(j, 1)][i] - co[j];
            for (; q[k].l <= q[k].r && q[k].v[q[k].r] < o; q[k].r--);
            q[k].v[++q[k].r] = o;
            q[k].id[q[k].r] = i;
        }
    }
    printf("%d", f[m]);
    return 0;
}