77 最长公共子序列 (lintcode)

注意：因为开的空间是length+1的，对于字符串的下标计算要-1

class Solution {
public:
    /*
     * @param A: A string
     * @param B: A string
     * @return: The length of longest common subsequence of A and B
     */
    int longestCommonSubsequence(string &A, string &B) {
        // write your code here
        int length1 = A.length();
        int length2 = B.length();
        vector<vector<int> > result(length1+1,vector<int>(length2+1));
        for(int i = 0;i <= length1;i++)
            result[i][0] = 0;
        for(int j = 0;j <= length2;j++)
            result[0][j] = 0;
        for(int i = 1;i <= length1;i++){
            for(int j = 1;j <= length2;j++){
                if(A[i-1] == B[j-1])
                    result[i][j] = result[i-1][j-1] + 1;
                else{
                    result[i][j] = max(result[i-1][j],result[i][j-1]);
                }
            }
        }
        return result[length1][length2];
    }
};