dp[i][j]:str[i , j]的最长回文子序列长度1、str[i]==str[j]:dp[i][j] = dp[i+1][j-1] + 2;2、str[i]!=str[j]:dp[i][j] = max(dp[i+1][j] , dp[i][j-1] )由于dp[i][j]依赖于dp[i+1][j-1]、dp[i+1][j]、dp[i][j-1],所以i要先遍历i较大的,即i从大到小遍历根据dp定义,j>=i,注意初始化dp[i][i]=1string str;for(int i=0;i<str.size();i++){ dp[i][i]=1; } ...