这个题只需要对数组循环一遍,记录最小值即可

class Solution {
public:
    int getDis(vector<int>& A, int n) {
        int minNum = A[0];
        int diff = 0;
        for (int i=1; i<n; i++) {
            if ( A[i] <=  minNum ) {
                minNum = A[i];
            }
            diff = max(diff, A[i]-minNum);
        }
        return diff;
    }
};