动态规划练习 14

题目：Bridging signals (POJ 1631)

链接：http://acm.pku.edu.cn/JudgeOnline/problem?id=1631

#include <iostream>
#include <vector>
#include <limits.h>

using namespace std;

// O(nlogn)
int LIS(const vector<int> &data)
{
    // if min_value[i] is j, means j is the min end value of all i length
    // increasing sequences.
    vector<int> min_value(data.size(), INT_MAX);
    int len = 1;

    for (size_t i = 0; i < data.size(); ++i)
    {
        int left = 1, right = len;

        while (left <= right)
        {
            int mid = (left + right) / 2;

            if (data[i] > min_value[mid])
            {
                left = mid + 1;
            }
            else
            {
                right = mid - 1;
            }
        }

        // right = left - 1
        // min_value[right] < data[i], min_value[left] >= data[i]
        if (data[i] < min_value[left])
        {
            min_value[left] = data[i];
        }

        if (len < left)
        {
            len = left;
        }
    }

    return len;
}

int main(int argc, char **argv)
{
    int cases, n;
    vector<int> data;

    cin >> cases;
    while (cases--)
    {
        cin >> n;
        while (n--)
        {
            int tmp;
            cin >> tmp;
            data.push_back(tmp);
        }

        cout << LIS(data) << endl;
        data.clear();
    }

    return 0;
}