Solution2.cpp

class Solution {
public:
    int findClosest(vector<string>& words, string word1, string word2) {
        unordered_map<string, vector<int>> d;
        for (int i = 0; i < words.size(); ++i) {
            d[words[i]].push_back(i);
        }
        vector<int> idx1 = d[word1], idx2 = d[word2];
        int i = 0, j = 0, m = idx1.size(), n = idx2.size();
        int ans = 1e5;
        while (i < m && j < n) {
            int t = abs(idx1[i] - idx2[j]);
            ans = min(ans, t);
            if (idx1[i] < idx2[j]) {
                ++i;
            } else {
                ++j;
            }
        }
        return ans;
    }
};