LeetCode126 Word Ladder II

来源：互联网发布：多益网络找回密码编辑：程序博客网时间：2024/06/05 01:31

详细见：leetcode.com/problems/word-ladder-ii

Java Solution: github

package leetcode;import java.util.ArrayList;import java.util.Arrays;import java.util.HashMap;import java.util.HashSet;/* * Given two words (beginWord and endWord), and a dictionary's word list,  * find all shortest transformation sequence(s) from beginWord to endWord, such that:Only one letter can be changed at a timeEach intermediate word must exist in the word listFor example,Given:beginWord = "hit"endWord = "cog" wordList = ["hot","dot","dog","lot","log"]Return  [    ["hit","hot","dot","dog","cog"],    ["hit","hot","lot","log","cog"]  ]Note:All words have the same length.All words contain only lowercase alphabetic characters. */import java.util.LinkedList;import java.util.List;import java.util.Queue;/** * @author      zxwtry * @email       zxwtry@qq.com * @project     OJ * @package     leetcode * @file        P126_WordLadderII.java * @type        P126_WordLadderII * @date        2016年12月13日 下午5:16:11 * @details     Solution: AC 204ms 65.85% */public class P126_WordLadderII {    public static void main(String[] args) {        String s = "hit";        String e = "cog";        String[] ss = {"hot","dot","dog","lot","log","cog"};        List<String> w = Arrays.asList(ss);        System.out.println(new Solution().findLadders(s, e, w));                    }static class Solution {    public List<List<String>> findLadders(String s, String t, List<String> w) {        List<List<String>> ans = new LinkedList<List<String>>();        if (s == null || t == null || w == null) {            if (s == null && t == null)                ans.add(Arrays.asList((String)null));            return ans;        }        if (s.equals(t)) {            ans.add(Arrays.asList(s));            return ans;        }        int sn = s.length();        if (w.size() == 0) return ans;        HashSet<String> nv = new HashSet<String>(w);        HashSet<String> hv = new HashSet<String>();        if (! nv.contains(t)) return ans;        nv.add(s);        Queue<String> q = new LinkedList<String>();        q.add(s);        HashMap<String, List<String>> m = new HashMap<String, List<String>>();        char[] cs = new char[sn];        boolean isFind = false;        while (! q.isEmpty()) {            int size = q.size();            while (size -- > 0) {                String n = q.poll();                for (int i = 0; i < sn; i ++) cs[i] = n.charAt(i);                for (int i = 0; i < sn; i ++) {                    for (char c = 'a'; c <= 'z'; c ++) {                        cs[i] = c;                        String nn = new String(cs);                        if (! nv.contains(nn)) continue;                        if (hv.add(nn)) q.add(nn);                        if (! m.containsKey(nn)) m.put(nn, new LinkedList<String>());                        m.get(nn).add(n);                        if (nn.equals(t)) isFind = true;                     }                    cs[i] = n.charAt(i);                }            }            if (isFind) break;            nv.removeAll(hv);            hv.clear();        }        System.out.println(m);        find(t, s, new LinkedList<String>(), m, ans);        return ans;    }        private void find(String t, String s, LinkedList<String> l, HashMap<String, List<String>> m,                List<List<String>> ans) {            l.addFirst(t);            if (t.equals(s)) {                ans.add(new LinkedList<String>(l));            } else {                for (String v : m.getOrDefault(t, new ArrayList<String>(0)))                    find(v, s, l, m, ans);            }            l.removeFirst();        }}}

CPP Solution: github

#pragma warning(disable:4786)#pragma warning(disable:4503)/*    url: leetcode.com/problems/word-ladder-ii    too many advanced data structure    use cpp    Solution: AC 259ms 51.41%*/#include <iostream>#include <queue>#include <set>#include <map>#include <vector>#include <string>using namespace std;class Solution {public:    void find(string t, string s, vector<string >& v, map<string, vector<string > >& m, vector<vector<string > >& ans) {        v.insert(v.begin(), t);        if (! t.compare(s)) {            ans.push_back(v);        } else if (m.count(t)) {            for (vector<string >::iterator iter = m[t].begin(); iter != m[t].end(); iter ++)                find(*iter, s, v, m, ans);        }        v.erase(v.begin());    }    vector<vector<string > > findLadders(string s, string t, vector<string>& w) {        vector<vector<string > > ans;        int sn = s.size() , i;        set<string > nv , hv;        for (i = 0; i < w.size(); i ++) nv.insert(w[i]);        map<string, vector<string > > m;        queue<string > q;        nv.insert(s);        q.push(s);        bool isFind = false;        while (! q.empty()) {            int size = q.size();            while (size -- > 0) {                string n = q.front();                string v = n;                q.pop();                for (i = 0; i < sn; i ++) {                    for (char c = 'a'; c <= 'z'; c ++) {                        v[i] = c;                        if (! nv.count(v)) continue;                        if (! hv.count(v)) {                            hv.insert(v);                            q.push(v);                        }                        m[v].push_back(n);                        if (! v.compare(t)) isFind = true;                    }                    v[i] = n[i];                }            }            if (isFind) break;            for (set<string >::iterator iter = hv.begin(); iter != hv.end(); iter ++)                nv.erase(*iter);            hv.clear();        }        vector<string > v;        find(t, s, v, m, ans);        return ans;    }};int main() {    string g[] = {"hot","dot","dog","lot","log","cog"};    string s = "hit", t = "cog";    vector<string > w;    int i;    for (i = 0; i < (sizeof(g)/sizeof(g[0])); i ++) w.push_back(g[i]);    vector<vector<string > > ans = Solution().findLadders(s, t, w);    for (i = 0; i < ans.size(); i ++) {        cout<<"+++++++++"<<endl;            for (int j = 0; j < ans[i].size(); j ++) {            cout<<ans[i][j]<<" ";        }        cout<<endl;    }    return 0;}

Python Solution: github

#coding=utf-8'''    url: leetcode.com/problems/word-ladder-ii    @author:     zxwtry    @email:      zxwtry@qq.com    @date:       2017年5月5日    @details:    Solution:  86ms 36.12%'''from jinja2._compat import unichrfrom re import searchclass Solution(object):    def backtrace(self, m, b, e, rec, ans):        rec.insert(0, e)        if b == e:            ans.append(list(rec))        else:            for v in m[e]:                self.backtrace(m, b, v, rec, ans)        rec.remove(rec[0])            def findLadders(self, b, e, w):        """        :type b: str        :type e: str        :type w: List[str]        :rtype: List[List[str]]        """        n = 0 if b == None else len(b)        if n == 0: return [[""]]        nv, hv = set(w), set()        m = {w[i]:set() for i in range(len(w))}        m[b] = set()        nv.add(b)        q, isFind = [b], False        while len(q) != 0:            size = len(q)            while size > 0:                 size = size-1                v = q.pop()                cs = [v[i] for i in range(n)]                for i in range(n):                    for k in range(26):                        cs[i] = unichr(97+k)                        cc = "".join(cs)                        if not (cc in nv): continue                        if cc == e: isFind = True                        if (cc not in hv):                            q.append(cc)                            hv.add(cc)                        m[cc].add(v)                    cs[i] = v[i]            if isFind: break            for vv in hv: nv.remove(vv)            hv.clear()        ans, rec = [], []        print(m)        self.backtrace(m, b, e, rec, ans)        return ans                if __name__ == "__main__":    b = 'hit'    e = 'cog'    w = ["hot","dot","dog","lot","log","cog"]    print(Solution().findLadders(b, e, w))

0 0