1. the Vector to do dynamic array is very convenient,
But to consider the code often accidentally crossed the line: v, v can not directly access the unassigned [i] = XXX, it is not defined, the value can not be left only push_back ().
And therefore can not jump assignment. This is not as flexible array.
2. the SET can automatically sort, eliminate duplication
But this is not accessible to s [i], even if provided it, * (it) is, but * (it + i) is wrong. So random access a lot of trouble. Recommendation back to the array.
3. the Map to-one mapping
But when the initial value can only assign one by one, very strenuous. Only in accordance mapped access, such mp [ 'c'] = 1;
If the hash chain to establish a similar, careful ah, anyway, I have not succeeded. Next try.
4. pair is also good, because the object is only one, do not visit it each have their own troubles (careful cross-border) to the array. But, the case can be used with a pair of vector
5. be updated. . .