[LintCode] 最长公共子序列

class Solution {
public:
    /**
     * @param A, B: Two strings.
     * @return: The length of longest common subsequence of A and B.
     */
    int longestCommonSubsequence(string A, string B) {
        // write your code here
        int m = A.length(), n = B.length();
        vector<int> cur(m + 1, 0);
        for (int j = 1; j <= m; j++) {
            int pre = 0;
            for (int i = 1; i <= m; i++) {
                int temp = cur[i];
                cur[i] = (A[i - 1] == B[j - 1]) ? pre + 1 : max(cur[i], cur[i - 1]);
                pre = temp;
            }
        }
        return cur[m];
    }
};