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  • hdu 1047 (big integer sum, fgets or scanf, make you func return useful infos) 分类: hdoj 2015-06-18 08:21 39人阅读 评论(0) 收藏

    errors made,
    boundary conditions, <= vs < ,
    decreasing vs increasing , ++, –,
    ‘0’/’1’ vs 0/1
    prototype of sum, return the starting position of c-style string containing the sum, just like sprintf return number of characters successfully read.

    p1=sum(p1,p2);

    and

    p=sprintf(p,"%09d",x);

    have some similarities.

    #include <cstdio>
    #include <cstring>
    
    char* sum(char *to, char *from) {
        static const int charzero='0',oublecharzero='0'+'0';
        int sz1=strlen(to), sz2=strlen(from), nszmax,nszmin, i,j, tmp,carry;
        if(sz1>=sz2) { nszmax=-sz2, nszmin=-sz1; }
        else { nszmax=-sz1, nszmin=-sz2; }
        to+=sz1, from+=sz2;
        for(carry=0,i=-1;i>=nszmax;--i) {
            tmp=carry+to[i]+from[i]-doublecharzero;
            to[i]=charzero+tmp%10; carry=tmp/10;
        }
        if(sz2>sz1) {
            for(j=i;j>=nszmin;--j) to[j]=from[j];
            sz1=sz2;
        }
        if(carry) {
            for(j=i;j>=nszmin && to[j]=='9';--j) to[j]='0';
            if(j<nszmin) { to[j]='1'; ++sz1; }
            else { ++to[j]; }
        }
        return to-sz1;
    }
    
    int main() {
        //freopen("input.txt","r",stdin);
        const int MAXSIZE=101;
        int ncase,i,j;
        char buf1[MAXSIZE+2]={0}, buf2[MAXSIZE+2]={0}, *p1,*p2;
        scanf("%d",&ncase);
        for(i=1;i<=ncase;++i) {
            p1=buf1+MAXSIZE, p2=buf2; p1[0]='0', p1[1]=0;
            while(scanf("%100s",p2)==1 && strcmp(p2,"0")!=0) {
                p1=sum(p1,p2);
            }
            puts(p1); if(i!=ncase) putchar('
    ');
        }
        return 0;
    }

    版权声明:本文为博主原创文章,未经博主允许不得转载。// p.s. If in any way improment can be achieved, better performance or whatever, it will be well-appreciated to let me know, thanks in advance.

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  • 原文地址:https://www.cnblogs.com/qeatzy/p/4716226.html
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