01背包 URAL 1073 Square Country

 

题目传送门

 1 /*  2  题意：问n最少能是几个数的平方和  3  01背包：j*j的土地买不买的问题  4  详细解释：http://www.cnblogs.com/vongang/archive/2011/10/07/2200721.html  5 */  6 #include <cstdio>  7 #include <algorithm>  8 #include <cmath>  9 #include <cstring> 10 using namespace std; 11 12 const int MAXN = 6e4 + 10; 13 const int INF = 0x3f3f3f3f; 14 int dp[MAXN]; 15 16 int main(void) //URAL 1073 Square Country 17 { 18 //freopen ("I.in", "r", stdin); 19 20 int n; 21 while (scanf ("%d", &n) == 1) 22  { 23 memset (dp, 0, sizeof (dp)); 24 for (int i=1; i<=n; ++i) 25  { 26 dp[i] = dp[i-1] + 1; 27 for (int j=2; j<=sqrt (n*1.0); ++j) 28  { 29 if (i >= j * j) dp[i] = min (dp[i], dp[i-j*j] + 1); 30 else break; 31  } 32  } 33 34 printf ("%d\n", dp[n]); 35  } 36 37 38 return 0; 39 }