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
", dp[n]);
35 }
36
37
38 return 0;
39 }