# include<stdio.h>
# include<malloc.h>
# include<string.h>
# define Max 10000

typedef struct stack
{
    char ch[Max];
    int top;
}STType;

STType *STInit()
{
    STType *s;
    s=(STType *)malloc(sizeof(STType));
    s->top=0;
    return s;
}

int EmptyST(STType *s)
{
    if(s->top==0)
        return 1;
    return 0;
}


void PushST(STType *s,char c)
{
    s->ch[++s->top]=c;
}

void PopST(STType *s)
{
    s->top--;
}

int main()
{
    STType *s;
    char *c;
    int n,i;
        s=STInit();
    scanf("%d",&n);
    while(n--)
    {
        scanf("%s",c);

        for(i=0;i<strlen(c);i++)
        {
            if(c[i]=='('||c[i]=='[')
                PushST(s,c[i]);
            if(c[i]==')'||c[i]==']')
            {
                if(EmptyST(s))
                {
                    printf("No\n");
                    break;
                }
                else if(s->ch[s->top]-c[i]==-1||s->ch[s->top]-c[i]==-2)
                {
                    PopST(s);
                }
                else
                {
                    printf("No\n");
                    break;
                }
            }
        }
        if(EmptyST(s))
            printf("Yes\n");
        else
            printf("No\n");
    }
    return 0;
}

break是想退出for循环，你是说的else if吧