Cracking The Coding Interview 9.7

//原文：
//
//	A circus is designing a tower routine consisting of people standing atop one another’s shoulders. For practical and aesthetic reasons, each person must be both shorter and lighter than the person below him or her. Given the heights and weights of each person in the circus, write a method to compute the largest possible number of people in such a tower.
//
//EXAMPLE:
//
//Input (ht, wt): (65, 100) (70, 150) (56, 90) (75, 190) (60, 95) (68, 110)
//
//Output: The longest tower is length 6 and includes from top to bottom: (56, 90) (60,95) (65,100) (68,110) (70,150) (75,190)
//
#include <iostream>
#include <algorithm>
using namespace std;

struct people
{
public:
	people(){};
	people(int _h, int _w){h = _h; w = _w;};
	int h;
	int w;
};

bool compare(const people &p1, const people &p2)
{
	if ( p1.h == p2.h)
	{
		return p1.w < p2.w;
	}
	return p1.h < p2.h;
}

//求最长子序列，参考http://www.csie.ntnu.edu.tw/~u91029/LongestIncreasingSubsequence.html#1
int getLIS(people *p, int size)
{
	int *length = new int[size];
	for (int i = 0; i<size ; i++)
	{
		length[i] = 1;
	}

	for (int i =0; i <size ; i++)
	{
		for (int j = i+1; j<size; j ++)
		{
			if (p[i].w < p[j].w)
			{
				length[j] = max(length[j], length[i] + 1);
			}
		}
	}

	int n = length[0];
	for (int i = 0; i < size; i++)
	{
		n = (length[i]>n? length[i]:n);
	}
	return n;
}

int main()
{
	people p[5] = {people(2,10), people(5,18), people(4,17), people(3,9), people(7,20)};
	for (int i = 0; i<5; i++)
	{
		cout<<p[i].h<<"   "<<p[i].w<<endl;
	}
	cout<<"============="<<endl;
	sort(p,p+5,compare);
	for (int i = 0; i<5; i++)
	{
		cout<<p[i].h<<"   "<<p[i].w<<endl;
	}
	cout<<getLIS(p,5)<<endl;
	return 0;
}