Pretty Sure

LeetCode - Ones and Zeroes

Question Definition

In the computer world, use restricted resource you have to generate maximum benefit is what we always want to pursue.

For now, suppose you are a dominator of m 0s and n 1s respectively. On the other hand, there is an array with strings consisting of only 0s and 1s.

Now your task is to find the maximum number of strings that you can form with given m 0s and n 1s. Each 0 and 1 can be used at most once.

LeetCode - Longest Palindromic Subsequence

Question Definition

Given a string s, find the longest palindromic subsequence’s length in s. You may assume that the maximum length of s is 1000.

Example 1:

Input:

"bbbab"
Output:
4
One possible longest palindromic subsequence is "bbbb".

Example 2:

Input:

"cbbd"
Output:
2
One possible longest palindromic subsequence is "bb".

Java Solution

public int longestPalindromeSubseq(String s) {
    int[][] dp = new int[s.length()][s.length()];
    for (int i = s.length() - 1; i >= 0; --i) {
        dp[i][i] = 1;
        for(int j = i + 1; j < s.length(); j++){
            if (s.charAt(i) == s.charAt(j)){
                dp[i][j] = dp[i + 1][j - 1] + 2;
            } else{
                dp[i][j] = Math.max(dp[i + 1][j], dp[i][j - 1]);
            }
        }
    }
    return dp[0][s.length() - 1];
}

LeetCode - Knight Probability in Chessboard

Question Definition

On an NxN chessboard, a knight starts at the r-th row and c-th column and attempts to make exactly K moves. The rows and columns are 0 indexed, so the top-left square is (0, 0), and the bottom-right square is (N-1, N-1).

A chess knight has 8 possible moves it can make, as illustrated below. Each move is two squares in a cardinal direction, then one square in an orthogonal direction.

Each time the knight is to move, it chooses one of eight possible moves uniformly at random (even if the piece would go off the chessboard) and moves there.

The knight continues moving until it has made exactly K moves or has moved off the chessboard. Return the probability that the knight remains on the board after it has stopped moving.

LeetCode - Is Subsequence

Question Definition

Given a string s and a string t, check if s is subsequence of t.

You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) string, and s is a short string (<=100).

A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie, “ace” is a subsequence of “abcde” while “aec” is not).

LeetCode - Delete and Earn

Question Definition

Given an array nums of integers, you can perform operations on the array.

In each operation, you pick any nums[i] and delete it to earn nums[i] points. After, you must delete every element equal to nums[i] - 1 or nums[i] + 1.

You start with 0 points. Return the maximum number of points you can earn by applying such operations.