DPL_1_D Longest Increasing Subsequence dp+二分查詢 最長遞增子序列
阿新 • • 發佈:2018-12-12
For a given sequence A = {a0, a1, ... , an-1}, find the length of the longest increasing subsequnece (LIS) in A.
An increasing subsequence of A is defined by a subsequence {ai0, ai1, ... , aik} where 0 ≤ i0 < i1 < ... < ik < n and ai0 < ai1 < ... < aik.
Input
n a0 a1 : an-1
In the first line, an integer n is given. In the next n lines, elements of A are given.
Output
The length of the longest increasing subsequence of A.
Constraints
- 1 ≤ n ≤ 100000
- 0 ≤ ai ≤ 109
Sample Input 1
5 5 1 3 2 4
Sample Output 1
3
Sample Input 2
3 1 1 1
Sample Output 2
1
n^2複雜度的演算法過不了此題。。。
需要dp+二分過。。。
程式碼如下:
#include <cstdio> #include <cstring> #include <algorithm> #include <iostream> using namespace std; const int maxn=100005; int n; int a[maxn]; int dp[maxn]; int Max; void init() { Max=1; dp[0]=a[0]; } int main() { scanf("%d",&n); for (int i=0;i<n;i++) scanf("%d",&a[i]); init(); for (int i=1;i<n;i++) { if(dp[Max-1]<a[i]) dp[Max++]=a[i]; else *lower_bound(dp,dp+Max,a[i])=a[i]; } printf("%d\n",Max); return 0; }