UVA 1149(p253)----Bin Packing

#include<iostream>#include<cstdio>#include<algorithm>#include<string>using namespace std;int a[100050],ans,t,cas,n,l,r,w;int main(){   // freopen("in.in","r",stdin);    scanf("%d",&t);    int cas=0;    while(t--)    {        cas++;ans=0;int num=0;        if(cas!=1) puts("");        scanf("%d",&n);scanf("%d",&w);        for(int i=0;i<n;i++)            scanf("%d",&a[i]);        sort(a,a+n);        l=0;r=n-1;        while(num<n&l<=r)        {            if(a[l]+a[r]<=w)            {                l+=1;r-=1;                ans++;num+=2;            }            else            {                r-=1;ans++;num+=1;            }           // cout<<l<<" "<<r<<endl;        }        printf("%d\n",ans);    }    return 0;}