79 最长公共子串

class Solution {
public:
    /**
     * @param A: A string
     * @param B: A string
     * @return: the length of the longest common substring.
     */
    int longestCommonSubstring(string &A, string &B) {
        // write your code here
    int n1=A.size(),n2=B.size();
     if (n1==0||n2==0)
     {
         return 0;
     }
     vector<vector<int>> dp(n1+1,vector<int>(n2+1,0));
    int maxl=-1;
     for (int i=1;i<=n1;i++)
     {
         for (int j=1;j<=n2;j++)
         {
            if (A[i-1]==B[j-1])
            {
                dp[i][j]=dp[i-1][j-1]+1;
            }
            maxl=max(maxl,dp[i][j]);
         }
     }

     return maxl;
    }
};