题目:uva 10069 Distinct Subsequences 题意:给出一个子串 x 和母串 s .求子串在母串中的不同序列的个数? 分析:定义dp[i][j]:x 的前 i 个字母在 s 的前 j 个字母中的出现次数: dp [ i ] [ j ] = dp [ i ] [ j - 1 ] ;          if ( x[ i ] == s [ j ] )                     dp[i][j]=add(dp[i-1][j-1],dp[i][j]); 注意点:1:…

题目连接:10069 - Distinct Subsequences 题目大意:给出两个字符串x (lenth < 10000), z (lenth < 100), 求在x中有多少个z. 解题思路:二维数组DP, 有类似于求解最长公共子序列, cnt[i][j]表示在x的前j个字符中有多少个z 前i个字符. 状态转移方程 1.x[j] != z[i]              cnt[i][j] = cnt[i][j - 1]; 2.x[j] == z[i]   cnt[i][j] = cnt…

考虑两个字符串,我们用dp[i][j]表示字串第到i个和字符串到第j个的总数,由于字串必须连续 因此dp[i][j]能够有dp[i][j-1]和dp[i-1][j-1]递推而来,而不能由dp[i-1][j]递推而来.而后者的条件 是字串的第i个和字符串相等. A subsequence of a given sequence is just the given sequence with some elements (possibly none) left out. Formally, give…

 题意 求母串中子串出现的次数(长度不超过1后面100个0  显然要用大数了) 令a为子串 b为母串 d[i][j]表示子串前i个字母在母串前j个字母中出现的次数   当a[i]==b[j]&&d[i-1][j-1]!=0时 d[i][j]=d[i-1][j-1]+d[i][j-1] (a[i]==b[j]时 子串前i个字母在母串前j个字母中出现的次数 等于 子串前i-1个字母在母串前j-1个字母中出现的次数 加上 子串前i个字母在母串前j-1个字母中出现的次数  a[i]!=b[j]…

Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative…

Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative…

Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative…

题目 Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relati…

Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative…

Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative…