01背包 URAL 1073 Square Country

 

题目传送门

/*
    题意：问n最少能是几个数的平方和
    01背包：j*j的土地买不买的问题
    详细解释：http://www.cnblogs.com/vongang/archive/2011/10/07/2200721.html
*/
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
using namespace std;

const int MAXN = 6e4 + 10;
const int INF = 0x3f3f3f3f;
int dp[MAXN];

int main(void)        //URAL 1073 Square Country
{
    //freopen ("I.in", "r", stdin);

    int n;
    while (scanf ("%d", &n) == 1)
    {
        memset (dp, 0, sizeof (dp));
        for (int i=1; i<=n; ++i)
        {
            dp[i] = dp[i-1] + 1;
            for (int j=2; j<=sqrt (n*1.0); ++j)
            {
                if (i >= j * j)    dp[i] = min (dp[i], dp[i-j*j] + 1);
                else    break;
            }
        }

        printf ("%d\n", dp[n]);
    }


    return 0;
}