poj 1948 Triangular Pastures

#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
using namespace std;
bool dp[45][800][800];
int a[45];
int main(){
int n,i,j,k;
int total=0;
scanf("%d",&n);
for(i=1;i<=n;i++){
scanf("%d",&a[i]);
total+=a[i];
}
memset(dp,false,sizeof(dp));
dp[0][0][0]=true;
double area=0,ans=0;
for(k=1;k<=n;k++){
for(i=0;i<=total/2;i++)
for(j=0;j<=(total-i)/2;j++){
dp[k][i][j]=dp[k-1][i][j];
if(i>=a[k]&&dp[k-1][i-a[k]][j]) dp[k][i][j]=true;
if(j>=a[k]&&dp[k-1][i][j-a[k]]) dp[k][i][j]=true;
}
}
for(i=0;i<=total/2;i++)
for(j=0;j<=(total-i)/2;j++)
if(dp
[i][j]){
int c=total-i-j;
if(i+j>c&&j+c>i&&c+i>j){
double half=(double)(i+j+c)/2.0;
area=sqrt((double)half*(half-i)*(half-j)*(half-c));
if(area>ans) ans=area;
//cout<<i<<" "<<j<<endl;
}
}
if(ans==0.0) printf("-1\n");
else printf("%d\n",(int)(ans*100));
return 0;
}