HDU_ACM_STEPS

1. Text Reverse

2. Rightmost Digit

3. Decimal System

4. AC Me
5. FatMouse's Trade

---

1. Text Reverse

#include

#include

char str[1002];

int main(){

int n;

scanf("%d",&n);

getchar();

while(n--){

fgets(str,1002,stdin);

int len = strlen(str);

int a = 0; //left border

int b = 0; //right border

int i = 0; //position counter

while(a < len){

i = a;

while(str[i]!=' '&& str[i]!='\n'){

i++;

}

b = i;

while(i-- && i >= a){

printf("%c",str[i]);

}

printf("%c",str[b]);

a = ++b;

}

}

return 0;

}

---

2.Rightmost Digit

#include

void my_pow(int a, int b){

long long unsigned result = 1;

long long unsigned tmp = 1;

while(b){

tmp *= a;

tmp %= 10;

if( b&1 ){

result *= tmp;

result %= 10;

}

b>>=1;

a = tmp;

}

printf("%d\n",result%10);

}

int main(){

int n;

scanf("%d",&n);

while(n--){

int a;

scanf("%d",&a);

if(a%4){

my_pow(a,a%4);

}else{

my_pow(a,4);

}

}

return 0;

}

---

3.Decimal System

#include

#include

#include

using namespace std;

int main(){

int N;

char a[1000];

int i,j;

int val;

char ch;

long long unsigned sum;

while(scanf("%d",&N)!=EOF){

getchar();

sum = 0;

while(N--){

i = 0;

while((ch = getchar())!='('){

a[i++] = ch;

}

j = i;

scanf("%d",&val);

getchar(); //')'

getchar(); //'enter'

i = 0;

while(j--){

sum += (a[i++]-'0')*(long long unsigned)pow((double)val,(double)j);

}

}

printf("%d\n",sum);

getchar();

}

return 0;

}

---

4.AC Me

#include

#include

#define MAXLINE 100001 

#define LIST 26

int count[LIST];

char line[MAXLINE];

int main(){

int i,j;

int len;

while(fgets(line,sizeof(line),stdin)){

len = strlen(line);

i = 0 ;

j = 0 ;

/* Refresh Counter[] */

memset(count,0,sizeof(count));

/* Counting */

while(i

j = line[i++]-'a';

if(j<27 && j>=0){

count[j]++;

}

}

/* Output */

i = 0;

while(i

printf("%c:%d\n",i+'a',count[i]);

i++;

}

printf("\n");

/* Empty line[] */

memset(line,-1,sizeof(line));

}//while:fgets

return 0;

}

---

5.FatMouse's Trade
浮点乘除运算最好在最后展开，否则精度问题会导致一直WA。
#include
#include
#include

typedef struct {
    int bean;
    int food;
    double val;        // javabean/food
}box;

void test(box* pData, int n)
{
    int i;
    for(i=0; i        printf("bean:%d; val: %lf ",(*(pData+i)).bean,(*(pData+i)).val);
    }
    printf("\n");
}

int cmp(const void *a, const void *b)
{
    return ((((*(box *)b).val-(*(box *)a).val)>0.0000) ? 1 : -1);
}

int main(){

    int M,N;
    double sum = 0;
    box * pData;

    while(scanf("%d %d",&M,&N) && (M>=0) && (N>=0))
    {
        pData = (box *)calloc(N,sizeof(box));
        assert(pData != NULL);

        int JavaBean,Food;

        int i = 0;
        while(i            scanf("%d %d",&JavaBean,&Food);
            (*(pData+i)).bean= JavaBean;
            (*(pData+i)).food= Food;
            (*(pData+i)).val = (double)JavaBean/Food;
            i++;
        }
   
        qsort(pData,N,sizeof(*pData),cmp);
//        test(pData,N);
       
        sum = 0;
        i = 0 ;
        while( M && i        {
            if(M>(*(pData+i)).food)
            {
                sum += (*(pData+i)).bean;
                M -= (*(pData+i)).food;
                //printf("M:%d; javabean=%lf\n",M,(*(pData+i)).food * (*(pData+i)).val);
                i++;
            }else{
                sum += M*(*(pData+i)).val;
                M = 0;
            //    printf("M:%d\n",M);
            }
        //    printf("i=%d\n",i);
        }
        printf("%.3lf\n",sum);
        free(pData);
    }
}