牛客寒假训练营2-H施魔法

思路

　　dp去维护前缀f[i-1] - ai的最小值

　　

CODE

 #include <bits/stdc++.h>
 #define dbg(x) cout << #x << "=" << x << endl

 using namespace std;
 typedef long long LL;

 template<class T>inline void read(T &res)
 {
     char c;T flag=;
     while((c=getchar())<''||c>'')if(c=='-')flag=-;res=c-'';
     while((c=getchar())>=''&&c<='')res=res*+c-'';res*=flag;
 }

 namespace _buff {
     const size_t BUFF =  << ;
     char ibuf[BUFF], *ib = ibuf, *ie = ibuf;
     char getc() {
         if (ib == ie) {
             ib = ibuf;
             ie = ibuf + fread(ibuf, , BUFF, stdin);
         }
         return ib == ie ? - : *ib++;
     }
 }

 int qread() {
     using namespace _buff;
     int ret = ;
     bool pos = true;
     char c = getc();
     for (; (c < '' || c > '') && c != '-'; c = getc()) {
         assert(~c);
     }
     if (c == '-') {
         pos = false;
         c = getc();
     }
     for (; c >= '' && c <= ''; c = getc()) {
         ret = (ret << ) + (ret << ) + (c ^ );
     }
     return pos ? ret : -ret;
 }

 const int kmaxn = ;
 LL f[kmaxn];
 LL a[kmaxn];
 int n,k;

 int main()
 {
     read(n);
     read(k);
     for(int i = ; i <= n; ++i) {
         read(a[i]);
     }

     sort(a+, a+n+);
     LL temp = -a[];
     for(int i = ; i < k; ++i) {
         f[i] =  << ;
     }
     for(int i = k; i <= n; ++i) {
         f[i] = temp + a[i];
         printf("f[%d]:%lld\n",i,f[i]);
         temp = min(temp, f[i-k+] - a[i-k+]);
         dbg(temp);
         printf("f[%d]:%lld\n",i,f[i]);
     }
     printf("%lld\n",f[n]);
     return ;
 }