练习1-9

int main(int argc, char** argv) {
    int nspace = 0;
    int c;
    while((c=getchar())!=EOF){
        if(c!=' '){
            nspace = 0;
            putchar(c);
        }
        if(c==' '){
            if(nspace==0){
                nspace=1;
                putchar(c);
            }
        }
    }
    return 0;