[LeetCode] 71.Simplify Path 简化路径
Given an absolute path for a file (Unix-style), simplify it.
For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"
click to show corner cases.
Corner Cases:
- Did you consider the case where path = "/../"?
In this case, you should return "/". - Another corner case is the path might contain multiple slashes '/' together, such as "/home//foo/".
In this case, you should ignore redundant slashes and return "/home/foo".
这道题让简化给定的路径，光根据题目中给的那一个例子还真不太好总结出规律，应该再加上两个例子 path = "/a/./b/../c/", => "/a/c"和path = "/a/./b/c/", => "/a/b/c"， 这样我们就可以知道中间是"."的情况直接去掉，是".."时删掉它上面挨着的一个路径，而下面的边界条件给的一些情况中可以得知，如果是空的话返回"/"，如果有多个"/"只保留一个。那么我们可以把路径看做是由一个或多个"/"分割开的众多子字符串，把它们分别提取出来一一处理即可，代码如下：
C++ 解法一:
class Solution {
public:
string simplifyPath(string path) {
vector<string> v;
int i = 0;
while (i < path.size()) {
while (path[i] == '/' && i < path.size()) ++i;
if (i == path.size()) break;
int start = i;
while (path[i] != '/' && i < path.size()) ++i;
int end = i - 1;
string s = path.substr(start, end - start + 1);
if (s == "..") {
if (!v.empty()) v.pop_back();
} else if (s != ".") {
v.push_back(s);
}
}
if (v.empty()) return "/";
string res;
for (int i = 0; i < v.size(); ++i) {
res += '/' + v[i];
}
return res;
}
};还有一种解法是利用了C语言中的函数strtok来分隔字符串，但是需要把string和char*类型相互转换，转换方法请猛戳这里。除了这块不同，其余的思想和上面那种解法相同，代码如下：
C 解法一:
class Solution {
public:
string simplifyPath(string path) {
vector<string> v;
char *cstr = new char[path.length() + 1];
strcpy(cstr, path.c_str());
char *pch = strtok(cstr, "/");
while (pch != NULL) {
string p = string(pch);
if (p == "..") {
if (!v.empty()) v.pop_back();
} else if (p != ".") {
v.push_back(p);
}
pch = strtok(NULL, "/");
}
if (v.empty()) return "/";
string res;
for (int i = 0; i < v.size(); ++i) {
res += '/' + v[i];
}
return res;
}
};C++中也有专门处理字符串的机制，我们可以使用stringstream来分隔字符串，然后对每一段分别处理，思路和上面的方法相似，参见代码如下：
C++ 解法二：
class Solution {
public:
string simplifyPath(string path) {
string res, t;
stringstream ss(path);
vector<string> v;
while (getline(ss, t, '/')) {
if (t == "" || t == ".") continue;
if (t == ".." && !v.empty()) v.pop_back();
else if (t != "..") v.push_back(t);
}
for (string s : v) res += "/" + s;
return res.empty() ? "/" : res;
}
};Java 解法二：
public class Solution {
public String simplifyPath(String path) {
Stack<String> s = new Stack<>();
String[] p = path.split("/");
for (String t : p) {
if (!s.isEmpty() && t.equals("..")) {
s.pop();
} else if (!t.equals(".") && !t.equals("") && !t.equals("..")) {
s.push(t);
}
}
List<String> list = new ArrayList(s);
return "/" + String.join("/", list);
}
}到此这篇关于C++实现LeetCode(71.简化路径)的文章就介绍到这了,更多相关C++实现简化路径内容请搜索编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程网！
