Longest Common Subsequence

general
1

Problem link: Online Judge

For some reason I get WA on some test case with this code:

#include <iostream>
#include <string>

using namespace std;

int LCS(string a, string b) {
    int alen = a.length();
    int blen = b.length();

    int dp[alen + 1][blen + 1];

    for (int i = 0; i <= alen; i++) {
        for (int j = 0; j <= blen; j++) {
            if (i == 0 || j == 0) dp[i][j] = 0;
            else if (a[i - 1] == b[j - 1]) dp[i][j] = dp[i - 1][j - 1] + 1;
            else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        }
    }
    return dp[alen][blen];
}


int main() {
    string x, y;
    while (cin >> x) {
        cin >> y;
        cout << LCS(x, y) << "\n";
    }
}