BZOJ1263: [SCOI2006]整数划分

#include<cstring>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstdio>
#define rep(i,l,r) for (int i=l;i<=r;i++)
#define down(i,l,r) for (int i=l;i>=r;i--)
#define clr(x,y) memset(x,y,sizeof(x))
#define maxn 20050
#define ll long long
using namespace std;
int n,l;
int ans[maxn];
ll read(){
    ll x=0,f=1; char ch=getchar();
    while (!isdigit(ch)) {
        if (ch==‘-‘) f=-1; ch=getchar();
    }
    while (isdigit(ch)){
        x=x*10+ch-‘0‘; ch=getchar();
    }
    return x*f;
}
void get(int x){
    rep(i,1,l) ans[i]*=x;
    rep(i,1,l) ans[i+1]+=ans[i]/10,ans[i]=ans[i]%10;
    while (ans[l+1]) {l++,ans[l+1]+=ans[l]/10,ans[l]%=10;}
    //while (ans[l+1]) l++;
}
int main(){
    n=read();
    l=1; ans[1]=1;
    while (n>4) {
        get(3); n-=3;
    }
    get(n);
    printf("%d\n",l);
    if (l<=100) {
        down(i,l,1) printf("%d",ans[i]);
    }
    else {
        down(i,l,l-99) printf("%d",ans[i]);
    }
    puts("");
    return 0;
}