不知道如何写的一道C++题

谁能帮我看一下这一题？我不知道怎样写。
原题：

img


代码：

#include 
using namespace std;
struct node {
    int r, h;
} b[200010];
int T,;
bool s[200010];
inline int read() {
    char c = getchar();
    int x = 0, s = 1;
    while (c < '0' || c > '9') {
        if (c == '-') s = -1;
        c = getchar();
    }
    while (c >= '0' && c <= '9') {
        x = x * 10 + c - '0';
        c = getchar();
    }
    return x * s;
}
bool cmp_r(node a, node b) {
    return a.r < b.r;
}
bool cmp_h(node a, node b) {
    return a.h > b.h;
}
int main() {
    T = read();
    for (int i = 0; i < T; i++) {
        b[i].r = read();
        b[i].h = read();
    }
    node *a = new node [T];
    memset(s, 0, sizeof(s));
    sort(b, b + T, cmp_r);
    for (int i = 0; i < T; i++)
        if (s[i]) a[i].h = b[i].h;
    sort(a, a + n, cmp_h);
    delete[] a;
    return 0;
}

贪心。

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 55;

int n;
int r[N], h[N];
int a[N];

bool cmp(int x, int y)
{
    return h[x] < h[y];
}

int main()
{
    scanf("%d", &n);

    for (int i = 1; i <= n; i ++ )
        scanf("%d%d", &r[i], &h[i]);

    int res = 0;
    for (int i = 1; i <= n; i ++ )
    {
        a[i] = 1; // 初始值为 1，因为至少可以垒出 1 层
        for (int j = 1; j < i; j ++ )
            if (r[i] > r[j])
                a[i] = max(a[i], a[j] + 1);

        res = max(res, a[i]);
    }

    printf("%d\n", res);

    return 0;
}