[leetcode]Simplify Path

用个stack来记录目录,如果要往前跳就pop就好了

不过要主意的是

...

.xxx

..xxx

这样的在unix是合法路径,开始没考虑TAT,以至于后面改的代码很乱,虽然AC了...

class Solution {
public:
    string simplifyPath(string path) {
        int size = path.size();
        if(size == 0) return "";
        int i = 0;
        stack<string> st;
        bool x = false;
        while(i < size){
            if(path[i] == '/'){
                while(i < size && path[i] == '/') i++;
                x = true;
                continue;
            }
            if(path[i] == '.'){
                if (i + 1 < size && path[i+1] == '.'){
                    if(i+2 < size && path[i+2] != '/'){
                        int start = i;
                        while(i < size && path[i] != '/') i++;
                        if(x) st.push(path.substr(start , i - start));
                        x = false;
                        continue;
                    }
                    if(!st.empty())st.pop();
                    i++;i++;
                }else{
                    if(i+1 < size && path[i+1] != '/'){
                        int start = i;
                        while(i < size && path[i] != '/') i++;
                        if(x) st.push(path.substr(start , i - start));
                        x = false;
                        continue;
                    }
                    i++;
                }
                x = false;
                continue;
            }
            int start = i;
            while(i < size && path[i] != '/' ){
                i++;
            }
            if(x) st.push(path.substr(start , i - start));
            x = false;
        }
        stack<string> ans;
        while(!st.empty()){
            ans.push(st.top());
            st.pop();
        }
        
        if(ans.empty()) return "/";
        string final = "";
        while(!ans.empty()){
            final += "/" + ans.top();
            ans.pop();
        }
        return final;
    }
};

 -------update June 22, 2014------

class Solution {
public:
    string simplifyPath(string path) {
        stack<string> dic;
        int size = path.size();
        int p = 0;
        while(p < size) {
            while(p < size && path[p] == '/') p++;
            int start = p;
            while(p < size && path[p] != '/') {
                p++;
            }
            if(p == start) break;
            string tmp = path.substr(start , p-start);
            if(tmp == ".") continue;
            if(tmp == "..") {
                if(dic.size() > 0) dic.pop();
                continue;
            }
            dic.push(tmp);
        }
        string ans = "";
        stack<string> rev;
        while(dic.size() > 0) {
            rev.push(dic.top());
            dic.pop();
        }
        while(rev.size() > 0) {
            ans += ("/" + rev.top());
            rev.pop();
        }
        if(ans == "") ans = "/";
        return ans;
    }
};

不知为啥之前的写那么复杂