BZOJ 1046 HAOI 2007 上升序列 DP

题目大意：给出一个序列，求出字典序最小的长度为k的上升序列。

思路：先随便搞搞求出一个数组f，表示从i开始最长的上升序列的长度。然后贪心的往后找，能放在当前位置就放。

CODE：

#define _CRT_SECURE_NO_WARNINGS

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define MAX 10010
#define INF 0x3f3f3f3f
using namespace std;

int src[MAX];
int f[MAX],max_length[MAX];
int cnt,asks;

bool cmp(int a,int b)
{
	return src[a] > src[b];
}

int ans[MAX];

int main()
{
	cin >> cnt;
	for(int i = 1; i <= cnt; ++i)
		scanf("%d",&src[i]);
	for(int i = cnt; i; --i) {
		int p = lower_bound(f + 1,f + cnt + 1,i,cmp) - f;
		max_length[i] = max_length[f[p - 1]] + 1;
		f[p] = i;
	}
	int length = 0;
	while(f[length + 1])	++length;
	cin >> asks;
	for(int x,i = 1; i <= asks; ++i) {
		scanf("%d",&x);
		if(x > length)	puts("Impossible");
		else {
			int temp = x,last = -INF;
			for(int i = 1; i <= cnt; ++i)
				if(max_length[i] >= temp && src[i] > last) {
					printf("%d",src[i]);
					last = src[i];
					--temp;
					if(temp)	putchar(' ');
					else {
						puts("");
						break;
					}
				}
		}
	}
	return 0;
}