AC 126

Author: eytter48

P126.cpp

@@ -0,0 +1,109 @@
+#include "header.h"
+#include <array>
+#include <bits/c++config.h>
+#include <cstddef>
+#include <cstring>
+#include <iostream>
+#include <vector>
+
+
+#define LEN 5001
+class Solution {
+public:
+    vector<vector<string>> findLadders(string beginWord, string endWord, vector<string>& wordList) {
+        const size_t &n = wordList.size();
+        bool *end = new bool[n]();
+        bool *visited = new bool[n]();
+        bool begin;
+        bool hasEnd = false;
+        queue<pair<int, vector<int>>> q;
+        for (size_t i=0; i<wordList.size(); i++) {
+            if (transfer(beginWord, wordList[i])) begin = true;
+            else begin=false;
+            if (transfer(endWord, wordList[i])) end[i] = true;
+            if (endWord == wordList[i]) hasEnd = true;
+            if (begin) {
+                vector<int> r = {(int)i};
+                q.emplace(i,r);
+                // visited[i] = true;
+            }
+        }
+        if (!hasEnd) return {};
+        if (transfer(beginWord, endWord)) {
+            vector<vector<string>> ret;
+            ret.push_back({beginWord, endWord});
+            return ret;
+        }
+        static int map[LEN][LEN];
+        for (size_t i=0; i<n; i++) 
+            map[i][0] = 0;
+        for (size_t i=0; i<n; i++) {
+            for (size_t j=i+1; j<n; j++) {
+                if (transfer(wordList[i], wordList[j])) {
+                    map[i][++map[i][0]] = j;
+                    map[j][++map[j][0]] = i;
+                }
+            }
+        }
+        bool found = false;
+        int minStep = 100;
+
+        vector<vector<string>> ret;
+        
+        while (!q.empty()) {
+            int _last = q.front().first;
+            vector<int> _step = q.front().second;
+            visited[_last] = true;
+            if (end[_last]&& _step.size()<=minStep) {
+                minStep = _step.size();
+                found = true;
+                vector<string> a;
+                a.push_back(beginWord);
+                for (const auto &i:_step)
+                    a.push_back(wordList[i]);
+                a.push_back(endWord);
+                ret.push_back(a);
+            }
+            else if (!found || _step.size()<=minStep)
+                for (int i=1; i<=map[_last][0]; i++) {
+                    int j = map[_last][i];
+                    if (!visited[j]) {
+                        _step.push_back(j);
+                        q.emplace(j, _step);
+                        _step.pop_back();
+                    }
+                }
+            q.pop();
+        }
+        return ret;
+    }
+private:
+    bool transfer(const string &a,const string &b) {
+        int differ = 0;
+        if (a.size()!=b.size()) return false;
+        for (size_t i=0; i<a.size(); i++)
+            if (a[i]!=b[i]) {
+                differ++;
+                if (differ>1) return false;
+            }
+        if (differ==1) 
+            return true;
+        else 
+            return false;
+    }
+};
+
+int main() {
+    string beginWord = "red";
+    string endWord = "tax";
+    vector<string> wordList = {"ted","tex","red","tax","tad","den","rex","pee"};
+    auto s = Solution().findLadders(beginWord, endWord, wordList);
+    for (auto v1:s) {
+        for (auto v2:v1) {
+            cout << v2 << " ";
+        }
+        cout << endl;
+    }
+
+    return 0;
+}