833. Find And Replace in String**
https://leetcode.com/problems/find-and-replace-in-string/
题目描述
To some string S, we will perform some replacement operations that replace groups of letters with new ones (not necessarily the same size).
Each replacement operation has 3 parameters: a starting index i, a source word x and a target word y. The rule is that if x starts at position i in the original string S, then we will replace that occurrence of x with y. If not, we do nothing.
For example, if we have S = "abcd" and we have some replacement operation i = 2, x = "cd", y = "ffff", then because "cd" starts at position 2 in the original string S, we will replace it with "ffff".
Using another example on S = "abcd", if we have both the replacement operation i = 0, x = "ab", y = "eee", as well as another replacement operation i = 2, x = "ec", y = "ffff", this second operation does nothing because in the original string S[2] = 'c', which doesn’t match x[0] = 'e'.
All these operations occur simultaneously. It’s guaranteed that there won’t be any overlap in replacement: for example, S = "abc", indexes = [0, 1], sources = ["ab","bc"] is not a valid test case.
Example 1:
Input: S = "abcd", indexes = [0,2], sources = ["a","cd"], targets = ["eee","ffff"]
Output: "eeebffff"
Explanation: "a" starts at index 0 in S, so it's replaced by "eee".
"cd" starts at index 2 in S, so it's replaced by "ffff".
Example 2:
Input: S = "abcd", indexes = [0,2], sources = ["ab","ec"], targets = ["eee","ffff"]
Output: "eeecd"
Explanation: "ab" starts at index 0 in S, so it's replaced by "eee".
"ec" doesn't starts at index 2 in the original S, so we do nothing.
Notes:
-
0 <= indexes.length = sources.length = targets.length <= 100 -
0 < indexes[i] < S.length <= 1000 - All characters in given inputs are lowercase letters.
C++ 实现 1
使用 res 保存最后的结果. 引入一个额外的指针 k 来指示 S 中的子字符串, 比如对于 index = i, 首先将 S[k, ... i) 子字符串加入到 res 中, 如果此时 S[i, ..., i + source.size()) 是否刚好等于 source, 那么还需要将目标字符串 target 加入到 res 中.
class Solution {
public:
string findReplaceString(string S, vector<int>& indexes, vector<string>& sources, vector<string>& targets) {
vector<pair<int, pair<string, string>>> record;
for (int i = 0; i < indexes.size(); ++ i)
record.push_back(make_pair(indexes[i], make_pair(sources[i], targets[i])));
std::sort(record.begin(), record.end(),
[] (const pair<int, pair<string,string>> &p, const pair<int, pair<string, string>> &q) {
return p.first < q.first;
});
string res;
int k = 0;
for (auto &p : record) {
auto end = p.first;
auto source = p.second.first;
auto target = p.second.second;
res += S.substr(k, end - k);
k = end;
if (S.substr(end, source.size()) == source) {
res += target;
k += source.size();
}
}
res += S.substr(k, S.size() - k);
return res;
}
};
