多选题：以下程序段（ ）的功能是求 $$s = 1+2+...+n-1$$。

以下程序段（ ）的功能是求 $$s = 1+2+...+n-1$$。



A.

int n = 10, s = 0;
for ( int i = 1; i < n; i++ ) {
s = s + i;
}

B.

int n = 10, s = 0;
for ( int i = 1; i < n; ++i ) {
s = s + i;
}

C.

int n = 10, s = 0;
for (int i = n-1; i > 0; ++i ) {
s = s + i;
}

D.

int n = 10, s = 0;
for ( int i = 1; i <= n-1; ++i ) {
s = s + i;
}

E.

int n = 10, s = 0;
for (int i = n-1; i > 0; i-- ) {
s = s + i;
}



答案：A B D E