洛谷P3030 [USACO11NOV]瓦交换Tile Exchanging

洛谷P3030 [USACO11NOV]瓦交换Tile Exchanging
f[i][j] 表示前i个物品，面积为j的最小代价
然后i降维

#include <bits/stdc++.h>
#define For(i,j,k) for(int i=j;i<=k;i++) 
#define Dow(i,j,k) for(int i=j;i>=k;i--) 
#define LL long long  
using namespace std ; 

const int N = 21,M=10011,inf=1e9 ; 
int n,m,start ; 
int a[N] ; 
int dp[2][M+11] ; 

inline int read() {
    int x = 0 , f = 1 ; 
    char ch = getchar() ; 
    while(ch<'0'||ch>'9') { if(ch=='-') f = -1 ; ch = getchar() ; } 
    while(ch>='0'&&ch<='9') { x = x * 10+ch-48 ; ch = getchar() ; } 
    return x * f ;  
}

int main() 
{
    n = read() ; m = read() ; 
    For(i,1,n) a[i]=read() ; 
    For(i,1,m) dp[0][i] = inf ; 
    dp[0][0]=0 ; 
    For(i,1,n) {
        For(j,0,m) {
            dp[i&1][j] = inf ; 
            for(int k=0;k*k<= j ;k++) 
              dp[i&1][j]=min(dp[i&1][j],dp[i&1^1][j-k*k] +abs(a[i]-k)*abs(a[i]-k) ) ; 
        }
    }
    if(dp[n&1][m]==inf) printf("-1
") ; 
    else printf("%d
",dp[n&1][m]) ; 
    return 0 ; 
}