luoguP1080 国王游戏 题解(NOIP2012)(贪心+高精)

#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#define il inline
#define rg register
#define ll long long
#define N 10001
#define inf 1000000010
using namespace std;
int n,a,b;
struct T{
    int le,ri;
}h[N];
ll now[N],ans[N],zs[N];
int len1,alen,flag;
il void re(rg int &x);
int cmp(const T &x,const T &y);
void solve(rg int k);
void add(rg int k);
int main()
{
    re(n),re(a),re(b);
    for(rg int i=1;i<=n;++i)
        re(h[i].le),re(h[i].ri);
    sort(h+1,h+n+1,cmp);
    while(a)
        now[++len1]=(a%10),a/=10;
    for(rg int i=1;i<=n;++i)
        solve(i),add(i);
    for(rg int i=len1;i>=1;--i){
        if((!flag)&&(!ans[i]))continue;
        cout<<ans[i];
        flag=1;
    }
    return 0;
}

il void re(rg int &x){
    rg int res=0,w=1;char c=getchar();
    while((c<‘0‘||c>‘9‘)&&c!=‘-‘)c=getchar();
    if(c==‘-‘)w=-1,c=getchar();
    while(c>=‘0‘&&c<=‘9‘)res=(res<<3)+(res<<1)+c-‘0‘,c=getchar();
    x=w*res;
}
int cmp(const T &x,const T &y){
    return (x.le*x.ri)<(y.le*y.ri);
}
void solve(rg int k){
    memset(zs,0,sizeof(zs));
    rg int c=h[k].ri,p=0;
    for(rg int i=len1;i>=1;--i){
        p=p*10+now[i];
        zs[i]=p/c,p%=c;
    }

    for(rg int i=len1;i>=1;--i){
        if(ans[i]==zs[i])continue;
        if(ans[i]>zs[i])break;
        memcpy(ans,zs,sizeof(zs));
        break;
    }
}//除以自己右手上的值统计
void add(rg int k){
    rg int c=h[k].le;
    for(rg int i=1;i<=len1;++i)
        now[i]*=c;
    for(rg int i=1;i<=len1;++i){
        if(now[i]>=10){
            rg int w=i;
            while(now[w]>=10){
                now[w+1]+=now[w]/10,now[w]%=10,w++;
                if(w>len1)len1=w;
            }
        }
    }
    while(now[len1+1]>=10)
        now[len1+1]=(now[len1]/10),now[len1]%=10,len1++;
}