Formatted question description: https://leetcode.ca/all/1754.html
1754. Largest Merge Of Two Strings
Level
Medium
Description
You are given two strings word1
and word2
. You want to construct a string merge
in the following way: while either word1
or word2
are non-empty, choose one of the following options:
- If
word1
is non-empty, append the first character inword1
tomerge
and delete it fromword1
.- For example, if
word1 = "abc"
andmerge = "dv"
, then after choosing this operation,word1 = "bc"
andmerge = "dva"
.
- For example, if
- If
word2
is non-empty, append the first character inword2
tomerge
and delete it fromword2
.- For example, if
word2 = "abc"
andmerge = ""
, then after choosing this operation,word2 = "bc"
andmerge = "a"
.
- For example, if
Return the lexicographically largest merge
you can construct.
A string a
is lexicographically larger than a string b
(of the same length) if in the first position where a
and b
differ, a
has a character strictly larger than the corresponding character in b
. For example, "abcd"
is lexicographically larger than "abcc"
because the first position they differ is at the fourth character, and d
is greater than c
.
Example 1:
Input: word1 = “cabaa”, word2 = “bcaaa”
Output: “cbcabaaaaa”
Explanation: One way to get the lexicographically largest merge is:
- Take from word1: merge = “c”, word1 = “abaa”, word2 = “bcaaa”
- Take from word2: merge = “cb”, word1 = “abaa”, word2 = “caaa”
- Take from word2: merge = “cbc”, word1 = “abaa”, word2 = “aaa”
- Take from word1: merge = “cbca”, word1 = “baa”, word2 = “aaa”
- Take from word1: merge = “cbcab”, word1 = “aa”, word2 = “aaa”
- Append the remaining 5 a’s from word1 and word2 at the end of merge.
Example 2:
Input: word1 = “abcabc”, word2 = “abdcaba”
Output: “abdcabcabcaba”
Constraints:
1 <= word1.length, word2.length <= 3000
word1
andword2
consist only of lowercase English letters.
Solution
Use two pointers index1
and index2
to point to indices of word1
and word2
, respectively. Each time compare the two characters at index1
and index2
. If the two characters are different, append the larger character to merge
. Otherwise, compare the remaining substrings of word1
and word2
starting from index1
and index2
respectively, and select the first character of the greater substring and append it to merge
. Finally, return merge
.
class Solution {
public String largestMerge(String word1, String word2) {
StringBuffer merge = new StringBuffer();
int length1 = word1.length(), length2 = word2.length();
int index1 = 0, index2 = 0;
while (index1 < length1 && index2 < length2) {
char c1 = word1.charAt(index1), c2 = word2.charAt(index2);
if (c1 > c2) {
merge.append(c1);
index1++;
} else if (c1 < c2) {
merge.append(c2);
index2++;
} else {
int temp1 = index1 + 1, temp2 = index2 + 1;
boolean flag = true;
while (temp1 < length1 && temp2 < length2) {
if (word1.charAt(temp1) == word2.charAt(temp2)) {
temp1++;
temp2++;
} else if (word1.charAt(temp1) > word2.charAt(temp2)) {
merge.append(c1);
index1++;
flag = false;
break;
} else {
merge.append(c2);
index2++;
flag = false;
break;
}
}
if (flag) {
if (temp2 == length2) {
merge.append(c1);
index1++;
} else {
merge.append(c2);
index2++;
}
}
}
}
while (index1 < length1) {
merge.append(word1.charAt(index1));
index1++;
}
while (index2 < length2) {
merge.append(word2.charAt(index2));
index2++;
}
return merge.toString();
}
}