https://leetcode.com/contest/9/problems/valid-word-square/
https://discuss.leetcode.com/topic/63387/java-ac-solution-easy-to-understand
Given a set of words (without duplicates), find all word squares you can build from them.
A sequence of words forms a valid word square if the kth row and column read the exact same string, where 0 ≤ k < max(numRows, numColumns).
For example, the word sequence
["ball","area","lead","lady"] forms a word square because each word reads the same both horizontally and vertically.b a l l
a r e a
l e a d
l a d y
Note:
- There are at least 1 and at most 1000 words.
- All words will have the exact same length.
- Word length is at least 1 and at most 5.
- Each word contains only lowercase English alphabet
a-z.
Example 1:
Input:
["area","lead","wall","lady","ball"]
Output:
[
[ "wall",
"area",
"lead",
"lady"
],
[ "ball",
"area",
"lead",
"lady"
]
]
Explanation:
The output consists of two word squares. The order of output does not matter (just the order of words in each word square matters).
Example 2:
Input:
["abat","baba","atan","atal"]
Output:
[
[ "baba",
"abat",
"baba",
"atan"
],
[ "baba",
"abat",
"baba",
"atal"
]
]
Explanation:
The output consists of two word squares. The order of output does not matter (just the order of words in each word square matters).https://discuss.leetcode.com/topic/63387/java-ac-solution-easy-to-understand
public boolean validWordSquare(List<String> words) {
if(words == null || words.size() == 0){
return true;
}
int n = words.size();
for(int i=0; i<n; i++){
for(int j=0; j<words.get(i).length(); j++){
if(j >= n || words.get(j).length() <= i || words.get(j).charAt(i) != words.get(i).charAt(j))
return false;
}
}
return true;
}