UVa 10131: Is Bigger Smarter?

动态规划题。类似UVa103 Stacking Box，都是题目给一种判断嵌套的方法然后求最长序列。提前对数据排序可以节省一些时间开销。

我的解题代码如下：

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

using namespace std;

#define MAXN 1005
int N;
int w[MAXN],s[MAXN];
int Rank[MAXN],Index[MAXN],NextInSeq[MAXN],LongLen[MAXN];
int cmp(const void *a, const void *b)
{
	int ai = *(int *)a, bi = *(int *)b;
	if(w[ai]!=w[bi]) return w[ai]-w[bi];
	return s[bi]-s[ai];
};
int dp(int n)
{
	if(LongLen[n]) return LongLen[n];
	int k = Index[n];
	for(int i=k+1; i<N; i++) if(w[n]<w[Rank[i]] && s[n]>s[Rank[i]]) if(LongLen[n]<dp(Rank[i]))
	{
		LongLen[n] = dp(Rank[i]);
		NextInSeq[n] = Rank[i];
	}
	return ++LongLen[n];
}
int main()
{
	N=0;
	while(scanf("%d %d",&w[N],&s[N])==2) N++;
	for(int i=0; i<N; i++) Rank[i] = i;
	qsort(Rank,N,sizeof(int),cmp);
	for(int i=0; i<N; i++) Index[Rank[i]] = i;
	memset(LongLen,0,sizeof(LongLen));

	int anslen = 0, ansi;
	for(int i=0; i<N; i++) if(anslen<dp(i)) { anslen = dp(i); ansi = i; }
	printf("%d
%d
",anslen,ansi+1);
	for(int i=1; i<anslen; i++) { ansi = NextInSeq[ansi]; printf("%d
",ansi+1); }
	return 0;
}