题解 | #最长无重复子数组#

map的简单运用

class Solution {
public:
    /**
     * 
     * @param arr int整型vector the array
     * @return int整型
     */
    map<int,int> mp;
    int maxLength(vector<int>& arr) {
        // write code here
        int maxlen = 1,first = 0;
        for(int i = 0,len = 0;i < arr.size();++i){
            if(mp.find(arr[i]) == mp.end()){
                mp[arr[i]] = i;
                len ++;
            }
            else{
                int start = mp[arr[i]];
                int templen = start - first + 1;
                len = len - templen + 1;
                //清除无效的标识
                for(int j = first;j <= start;++j)
                    mp.erase(arr[j]);
                mp[arr[i]] = i;
                first = start + 1;
            }
            maxlen = max(maxlen,len);
        }
        return maxlen;
    }
};