Partition Labels Problem
Description
LeetCode Problem 763.
You are given a string s. We want to partition the string into as many parts as possible so that each letter appears in at most one part.
Return a list of integers representing the size of these parts.
Example 1:
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Input: s = "ababcbacadefegdehijhklij"
Output: [9,7,8]
Explanation:
The partition is "ababcbaca", "defegde", "hijhklij".
This is a partition so that each letter appears in at most one part.
A partition like "ababcbacadefegde", "hijhklij" is incorrect, because it splits s into less parts.
Example 2:
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Input: s = "eccbbbbdec"
Output: [10]
Constraints:
- 1 <= s.length <= 500
- s consists of lowercase English letters.
Sample C++ Code
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class Solution {
public:
vector<int> partitionLabels(string S) {
vector<int> res, pos(26, 0);
for (auto i = 0; i < S.size(); ++i)
pos[S[i] - 'a'] = i;
for (auto i = 0, idx = INT_MIN, last_i = 0; i < S.size(); ++i) {
idx = max(idx, pos[S[i] - 'a']);
if (idx == i)
res.push_back(i - exchange(last_i, i + 1) + 1);
}
return res;
}
};