Description
Problem C: Edit Step Ladders
An edit step is a transformation from one word x to another word y such that x and y are words in the dictionary, and x can be transformed to y by adding, deleting, or changing one letter. So the transformation from dig to dog or from dog to do are both edit steps. An edit step ladder is a lexicographically ordered sequence of words w1, w2, ... wn such that the transformation from wi to wi+1 is an edit step for all i from 1 to n-1.
For a given dictionary, you are to compute the length of the longest edit step ladder.
Input
The input to your program consists of the dictionary - a set of lower case words in lexicographic order - one per line. No word exceeds 16 letters and there are no more than 25000 words in the dictionary.Output
The output consists of a single integer, the number of words in the longest edit step ladder.Sample Input
cat dig dog fig fin fine fog log wine
Sample Output
5 题意:给你一个递增的字符串数组,给你三种操作方法变成其它的串,问你最长的可能 思路:hash+二分,dp[i]表示从i開始的串的最长变化可能。记忆化搜索#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> using namespace std; const int MAXN = 25010; const int HASH = 1000010; int n, head[HASH], next[MAXN], f[MAXN]; char b[MAXN][20], temp[20]; int hash(char *s) { int v = 0,seed = 131; while (*s) v = v * seed + *(s++); return (v & 0x7fffffff) % HASH; } void insert(int s) { int h = hash(b[s]); next[s] = head[h]; head[h] = s; } int search(char *s) { int i,h = hash(s); for (i = head[h]; i != -1; i = next[i]) if (!strcmp(b[i],s)) break; return i; } void add(char *s, int p, int d) { int i = 0, j = 0; while (i < p) temp[j++] = s[i++]; temp[j++] = 'a' + d; while (s[i]) temp[j++] = s[i++]; temp[j] = '