三、阅读程序-2

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#include <algorithm>
#include <iostream>
using namespace std;

int n, a[1005];

struct Node
{
    int h, j, m, w;

    Node(const int _h, const int _j, const int _m, const int _w):
    h(_h), j(_j), m(_m), w(_w)
    { }

    Node operator+ (const Node &o) const
    {
        return Node(
        max(h, w + o.h),
        max(max(j, o.j), m + o.h),
        max(m + o.w, o.m),
      w + o.w);
    }
};

Node solve1(int h, int m)
{
    if (h > m)
        return Node(-1, -1, -1, -1);
    if (h == m)
        return Node(max(a[h], 0), max(a[h], 0), max(a[h], 0), a[h]);
    int j = (h + m) >> 1;
    return solve1(h, j) + solve1(j + 1, m);
}

int solve2(int h, int m)
{
    if (h > m)
        return -1;
    if (h == m)
        return max(a[h], 0);
    int j = (h + m) >> 1;
    int wh = 0, wm = 0;
    int wht = 0, wmt = 0;
    for (int i = j; i >= h; i--) {
        wht += a[i];
        wh = max(wh, wht);
    }
    for (int i = j + 1; i <= m; i++) {
        wmt += a[i];
        wm = max(wm, wmt);
    }
    return max(max(solve2(h, j), solve2(j + 1, m)), wh + wm);
}

int main(){
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    cout << solve1(1, n).j << endl;
    cout << solve2(1, n) << endl;
    return 0;
}