2.1.4 Sorting A Three-Valued Sequence

/* ID: zhangzz4 PROG: sort3 LANG: C++ */ #include<stdio.h> const int N=1001; int _min(int a,int b){return a>b?b:a;} int a[N]; int main() { freopen("sort3.in","r",stdin); freopen("sort3.out","w",stdout); int n,n1=0,n2=0; scanf("%d",&n); for(int i=0;i<n;i++) { scanf("%d",&a[i]); if(a[i]==1) n1++; if(a[i]==2) n2++; } int ans=0,n12=0,n21=0,n32=0; for(int i=0;i<n1;i++) { if(a[i]>1) ans++; n21+=a[i]==2; } for(int i=n1;i<n1+n2;i++) { if(a[i]>2) ans++; n32+=a[i]==3; n12+=a[i]==1; } printf("%d/n",ans+n12-_min(n21,n12)); }