zoukankan      html  css  js  c++  java
  • [LintCode] Longest Increasing Continuous subsequence II

    Give you an integer matrix (with row size n, column size m),find the longest increasing continuous subsequence in this matrix. (The definition of the longest increasing continuous subsequence here can start at any row or column and go up/down/right/left any direction).

    Example

    Given a matrix:

    [
      [1 ,2 ,3 ,4 ,5],
      [16,17,24,23,6],
      [15,18,25,22,7],
      [14,19,20,21,8],
      [13,12,11,10,9]
    ]
    

    return 25

    Challenge

    O(nm) time and memory.

    备忘录,dp[i][j] = max{dp[i-1][j], dp[i][j-1], dp[i+1][j], dp[i][j+1]} + 1。

     1 class Solution {
     2 public:
     3     /**
     4      * @param A an integer matrix
     5      * @return  an integer
     6      */
     7     bool isValid(vector<vector<int>> &A, int x, int y) {
     8         return x >= 0 && x < A.size() && y >= 0 && y < A[0].size();
     9     }
    10     int dfs(vector<vector<int>> &A, vector<vector<int>> &dp, int x, int y) {
    11         if (dp[x][y] != -1) return dp[x][y];
    12         const int dx[4] = {0, 1, 0, -1};
    13         const int dy[4] = {1, 0, -1, 0};
    14         int tmp = 1;
    15         for (int i = 0; i < 4; ++i) {
    16             int xx = x + dx[i], yy = y + dy[i];
    17             if (isValid(A, xx, yy) && A[x][y] > A[xx][yy]) tmp = max(tmp, dfs(A, dp, xx, yy) + 1);
    18         }
    19         dp[x][y] = tmp;
    20         return dp[x][y];
    21     }
    22     int longestIncreasingContinuousSubsequenceII(vector<vector<int>>& A) {
    23         // Write your code here
    24         if (A.empty() || A[0].empty()) return 0;
    25         int res = 0;
    26         vector<vector<int>> dp(A.size(), vector<int>(A[0].size(), -1));
    27         for (int i = 0; i < A.size(); ++i) {
    28             for (int j = 0; j < A[0].size(); ++j) {
    29                 res = max(res, dfs(A, dp, i, j));
    30             }
    31         }
    32         return res;
    33     }
    34 };
  • 相关阅读:
    java第五周作业
    ajax初探--实现简单实时验证
    Html+CSS二周目--->常用概念
    Html+CSS--->第一周初探
    Servlet细节整合
    多线程基础
    设计模式之单例模式(Singleton)
    配置文件Java读写
    Java基础之IO流
    JDBC基础
  • 原文地址:https://www.cnblogs.com/easonliu/p/4586518.html
Copyright © 2011-2022 走看看