uva11121- -2进制

题目链接 http://acm.hust.edu.cn/vjudge/problem/19593

 

解题思路

把数的2进制写出来。

用-2进制套进去，比较两者的关系，可得出结论。

 

代码

#include<stdio.h>
#include<string.h> 
#include<stdlib.h>
const int maxLen = 205;
int base2[maxLen];
void GetBase2(int num, int &w)
{
    while(num != 0) {
        base2[++w] = num % 2;
        num /= 2;
    }
}
void ChangeBase(int num, int &w)
{
    if(num > 0) {
        for(int i=0; i<=w; i++) if(i % 2 == 1) {
            int jin = 0, j = i + 1;
            if(base2[i]) base2[j]++; 
            jin = base2[j] / 2; base2[j] %= 2;
            while(jin) { 
                j++;
                base2[j] += jin; 
                jin = base2[j] / 2; base2[j] %= 2; 
            }
            w = w > j ? w : j;
        }
    }
    else if(num < 0) {
        for(int i=0; i<=w; i++) if(i % 2 == 0) {
            int jin, j = i + 1;
            if(base2[i]) base2[j]++; 
            jin = base2[j] / 2; base2[j] %= 2;
            while(jin) {
                j++;
                base2[j] += jin; 
                jin = base2[j] / 2; base2[j] %= 2; 
            }
            w = w > j ? w : j;
        }
    }
    else w = 0;
}
int main()
{
    int cases, t = 1;
    int wei;
    scanf("%d", &cases);
    while(cases--) {
        int number;
        wei = -1;
        memset(base2, 0, sizeof(base2));
        scanf("%d", &number);
        GetBase2(abs(number), wei);
        ChangeBase(number, wei);
        printf("Case #%d: ", t);
        for(int i=wei; i>=0; i--) printf("%d", base2[i]);
        printf("\n");
        t++;
    }
    return 0;
}