leetcode 418

问题

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:

  1. A word cannot be split into two lines.
  2. The order of words in the sentence must remain unchanged.
  3. Two consecutive words in a line must be separated by a single space.
  4. Total words in the sentence won’t exceed 100.
  5. Length of each word is greater than 0 and won’t exceed 10.
  6. 1 ≤ rows, cols ≤ 20,000.

Example 1:

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

Output: 
1

Explanation:
hello---
world---

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

Example 2:

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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:

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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.

分析

属于那种直观上感觉有思路，但是又感觉代码写起来很费劲的题。要总结一下这类题，找到答题的技巧。

代码

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class Solution {
public:
    int wordsTyping(vector<string>& sentence, int rows, int cols) {
        string s = "";
        for (string &sen: sentence) {
            s += sen + " ";
        }
        int l = s.size();
        int start = 0;
        for (int i = 0; i < rows; ++i) {
            start += cols;
            while (start >= 0 && s[start%l] != ' ')
                start--;
            start++;
        }
        return start/l;
    }
};