P1120 小木棍

题面

https://www.luogu.org/problem/P1120

题解

#include<iostream>
#include<algorithm>
#include<set>
#include<cstdlib>
#include<cstring>
#include<cstdio>
using namespace std;

int n,a[200],m,sum,maxt,zushu;

struct node{
  int v,c;
} b[200];

bool cmp(int x,int y){
  return x>y;
}

void dfs(int s0,int num,int rest) {
  if (num==zushu+1) {
    printf("%d\n",maxt);
    exit(0);
  }
  if (s0>m) return;
  int i,s=-1,l=s0,r=m,mid;
  while (l<=r) {
    mid=(l+r)/2;
    if (b[mid].v<=rest) s=mid,r=mid-1; else l=mid+1;
  }
  if (s==-1) return;
  if (b[s].v==rest && b[s].c>0) {
    b[s].c--;
    dfs(1,num+1,maxt);
    b[s].c++;
  }
  else {
    for (i=max(s0,s);i<=m;i++) if (b[i].c>0) {
      b[i].c--;
      dfs(i,num,rest-b[i].v);
      b[i].c++;
      if (rest==maxt) return;
    }
  }
}

int main(){
  int i,j,t,cnt=0,mx=0;
  cin>>n;
  for (i=1;i<=n;i++){
    cin>>t;
    if (t<=50) a[++cnt]=t;
  }
  n=cnt;
  sort(a+1,a+n+1,cmp);
  for (i=1;i<=n;i++) sum+=a[i],mx=max(mx,a[i]);

  cnt=0;
  for (i=1;i<=n;) {
    b[++cnt].c=0;
    b[cnt].v=a[i];
    for (j=i;a[j]==a[i];j++) b[cnt].c++;
    i=j;
  }
  m=cnt;

  for (maxt=mx;maxt<=sum/2;maxt++) if (sum%maxt==0) {
    zushu=sum/maxt;
    dfs(1,1,maxt);
  }
  printf("%d",sum);
}