Solution.cpp

class Solution {
public:
    int findRotateSteps(string ring, string key) {
        int m = key.size(), n = ring.size();
        vector<int> pos[26];
        for (int j = 0; j < n; ++j) {
            pos[ring[j] - 'a'].push_back(j);
        }
        int f[m][n];
        memset(f, 0x3f, sizeof(f));
        for (int j : pos[key[0] - 'a']) {
            f[0][j] = min(j, n - j) + 1;
        }
        for (int i = 1; i < m; ++i) {
            for (int j : pos[key[i] - 'a']) {
                for (int k : pos[key[i - 1] - 'a']) {
                    f[i][j] = min(f[i][j], f[i - 1][k] + min(abs(j - k), n - abs(j - k)) + 1);
                }
            }
        }
        int ans = 1 << 30;
        for (int j : pos[key[m - 1] - 'a']) {
            ans = min(ans, f[m - 1][j]);
        }
        return ans;
    }
};