백준 14003번 : 가장 긴 증가하는 부분 수열 5 - LIS

https://www.acmicpc.net/problem/14003

14003번: 가장 긴 증가하는 부분 수열 5

 

 

#include <bits/stdc++.h>

#define MX 1'000'003
using namespace std;


int n;
vector<int> v, ans, forPrint;
int arr[MX], indexArr[MX];

int lower_bound(int val) {
    int st = 0;
    int en = ans.size() - 1;

    while (st <= en) {
        int mid = (st + en) / 2;
        if (ans[mid] >= val) {
            en = mid - 1;
        } else {
            st = mid + 1;
        }
    }
    return st;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> arr[i];

        int idx = lower_bound(arr[i]);
        if (idx == ans.size()) {
            ans.push_back(arr[i]);
        } else {
            ans[idx] = arr[i];
        }

        indexArr[i] = idx;
    }

    int answer = ans.size();
    cout << answer << '\n';

    for (int i = n - 1; i >= 0; i--) {
        if (indexArr[i] == answer - 1) {
            forPrint.push_back(arr[i]);
            answer--;
        }
    }

    for (int i = forPrint.size() - 1; i >= 0; i--) {
        cout << forPrint[i] << ' ';
    }

    return 0;
}