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Sentence_Screen_Fitting.md

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418. Sentence Screen Fitting

Given a rows x cols screen and a sentence represented by a list of non-empty words, find how many times the given sentence can be fitted on the screen.

Note:

  • A word cannot be split into two lines.
  • The order of words in the sentence must remain unchanged.
  • Two consecutive words in a line must be separated by a single space.
  • Total words in the sentence won't exceed 100.
  • Length of each word is greater than 0 and won't exceed 10.
  • 1 ≤ rows, cols ≤ 20,000.

Example 1:

Input:
rows = 2, cols = 8, sentence = ["hello", "world"]

Output: 
1

Explanation:
hello---
world---

The character '-' signifies an empty space on the screen.

Example 2:

Input:
rows = 3, cols = 6, sentence = ["a", "bcd", "e"]

Output: 
2

Explanation:
a-bcd- 
e-a---
bcd-e-

The character '-' signifies an empty space on the screen.

Example 3:

Input:
rows = 4, cols = 5, sentence = ["I", "had", "apple", "pie"]

Output: 
1

Explanation:
I-had
apple
pie-I
had--

The character '-' signifies an empty space on the screen.

Method:

brute force, O(rc), TLE:

class Solution(object):
    def wordsTyping(self, sentence, rows, cols):
        """
        :type sentence: List[str]
        :type rows: int
        :type cols: int
        :rtype: int
        """
        i=0
        cnt=0
        for r in range(rows):
            col=cols
            while col>=len(sentence[i]):
                col-=len(sentence[i])+1
                i+=1
                if i==len(sentence):
                    cnt+=1
                    i=0
        return cnt

Solution:

O(r+len(sentence)), use dp to record next movement:

class Solution(object):
    def wordsTyping(self, sentence, rows, cols):
        """
        :type sentence: List[str]
        :type rows: int
        :type cols: int
        :rtype: int
        """
        s=' '.join(sentence)+' '
        dp=[0]*len(s)
        for i in range(1, len(dp)):
            dp[i]=dp[i-1]-1 if s[i]!=' ' else 1
        cnt=0
        for r in range(rows):
            cnt+=cols
            cnt+=dp[cnt%len(s)]
        return cnt/len(s)