418. Sentence Screen Fitting

Given a rows x cols screen and a sentence represented by a list of 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 won't exceed 10.
6. 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.
分析：

public class Solution {
    // public int wordsTyping(String[] sentence, int rows, int cols) {
    //     String s = String.join("_", sentence) + "_";
    //     int len = s.length();
    //     int count = 0;
    //     int[] map = new int[len];
    //     for (int i = 1; i < len; ++i) {
    //         // if charAt(i) == '_', which means we saved an extra space
    //         map[i] = s.charAt(i) == '_' ? 1 : map[i-1] - 1;
    //     }
    //     for (int i = 0; i < rows; ++i) {
    //         count += cols;
    //         count += map[count % len];
    //     }
    //     return count / len;
    // }
    public int wordsTyping(String[] sentence, int rows, int cols) {
        String s = String.join(" ", sentence) + " ";
        int count = 0;
        int length = s.length();
        for (int i = 0; i < rows; i++) {
            count += cols;
            if (s.charAt(count % length) == ' ') {
                count++;
            } else {
                while (count >= 0 && s.charAt(count % length) != ' ') {
                    count--;
                }
                count++;
            }
        }
        return count / length;
    }
}