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  • POJ 2533 Longest Ordered Subsequence 简单DP

    题目链接http://poj.org/problem?id=2533

    题目大意:求最长递增子序列。。。

    解题思路:dp[i] = dp[j] + 1  a[i] > a[j] && dp[j] + 1 > dp[i]

    注意初始化为1!

    代码:

     1 const int inf = 0x3f3f3f3f;
     2 const int maxn = 1e3 + 5;
     3 int n, a[maxn];
     4 int dp[maxn];
     5 
     6 void solve(){
     7     memset(dp, 0, sizeof(dp));
     8     for(int i = 0; i <= n; i++) dp[i] = 1;
     9     int ans = 1;
    10     for(int i = 1; i <= n; i++){
    11         for(int j = 1; j < i; j++){
    12             if(a[j] < a[i] && dp[j] + 1 > dp[i])
    13                 dp[i] = dp[j] + 1;
    14         }
    15         ans = max(ans, dp[i]);
    16     }
    17     printf("%d
    ", ans);
    18 }
    19 int main(){
    20     scanf("%d", &n);
    21     for(int i = 1; i <= n; i++){
    22         scanf("%d", &a[i]);
    23     }
    24     solve();
    25 }

    题目:

    Longest Ordered Subsequence
    Time Limit: 2000MS   Memory Limit: 65536K
    Total Submissions: 54539   Accepted: 24426

    Description

    A numeric sequence of ai is ordered if a1 < a2 < ... < aN. Let the subsequence of the given numeric sequence (a1a2, ..., aN) be any sequence (ai1ai2, ..., aiK), where 1 <= i1 < i2 < ... < iK <= N. For example, sequence (1, 7, 3, 5, 9, 4, 8) has ordered subsequences, e. g., (1, 7), (3, 4, 8) and many others. All longest ordered subsequences are of length 4, e. g., (1, 3, 5, 8).

    Your program, when given the numeric sequence, must find the length of its longest ordered subsequence.

    Input

    The first line of input file contains the length of sequence N. The second line contains the elements of sequence - N integers in the range from 0 to 10000 each, separated by spaces. 1 <= N <= 1000

    Output

    Output file must contain a single integer - the length of the longest ordered subsequence of the given sequence.

    Sample Input

    7
    1 7 3 5 9 4 8

    Sample Output

    4
    

    Source

    Northeastern Europe 2002, Far-Eastern Subregion
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  • 原文地址:https://www.cnblogs.com/bolderic/p/7366456.html
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