UVa 100131 Is Bigger Smarter（LIS）

题意：

有N头象，找出其中体重从小到大，智商从高到底的X只，并输出。

思路：

先对于象的体重进行从小到大排序，然后对其智商进行最长下降子序列选择

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <algorithm>

using namespace std;

struct Node {
    int i;
    int w, s;

    Node(int _w, int _s, int _i) : w(_w), s(_s), i(_i) { }

    friend bool operator < (const Node &a, const Node &b)
    { return a.w < b.w; }
};

vector<Node> ele;

int dp[1010], pre[1010];

int main()
{
    int w, iq;
    int id = 0;
    while (scanf("%d %d", &w, &iq) != EOF)
    {
        ele.push_back(Node(w, iq, id + 1));
        ++id;
    }
    ele.push_back(Node(0, 0, 0));

    sort(&ele[0], &ele[id]);
    
    memset(dp, 0, sizeof(dp));
    memset(pre, 0, sizeof(pre));

    
    int mm, pos;

    dp[0] = 1, pre[0] = -1;
    mm = 1, pos = 0;

    for (int i = 1; i < id; ++i)
    {
        dp[i] = 1;
        for (int j = 0; j < i; ++j)
        {
            if (ele[i].s < ele[j].s && ele[i].w > ele[j].w && dp[i] <= dp[j])
                dp[i] = dp[j] + 1, pre[i] = j;

            if (mm <= dp[i])
                mm = dp[i], pos = i;
        }
    }
    vector<int> p;
    for (int i = 0; i < mm; ++i)
        p.push_back(ele[pos].i), pos = pre[pos];

    printf("%d\n", mm);
    for (int i = mm - 1; i >= 0; --i)
        printf("%d\n", p[i]);

    return 0;
}