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poj 3132 Sum of Different Primes

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poj 3132 Sum of Different Primes

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <cmath>using namespace std;#define maxn 1200#define maxr 20bool is[maxn];int prm[maxn];int n, r, tot;int f[maxr][maxn][maxn];int w[maxn];int getprm(int n){    int i, j, k = 0;    int s, e = (int) (sqrt(0.0 + n) + 1);    memset(is, 1, sizeof(is));    prm[k++] = 2;    is[0] = is[1] = 0;    for (i = 4; i < n; i += 2)        is[i] = 0;    for (i = 3; i < e; i += 2)        if (is[i])        { prm[k++] = i; for (s = i * 2, j = i * i; j < n; j += s)     is[j] = 0;        }    for (; i < n; i += 2)        if (is[i]) prm[k++] = i;    return k;}int work(){    int i = 0;    while (i < tot && prm[i] <= n)        i++;    int m = i;    memset(w, 0, sizeof(w));    for (int i = 0; i < m; i++)        w[i + 1] = prm[i];    for (int i = 0; i <= m; i++)        f[0][i][0] = 1;    for (int i = 1; i <= r; i++)    {        for (int j = 1; j <= m; j++) for (int k = 0; k <= n; k++) {     f[i][j][k] = f[i][j - 1][k];     if (k - w[j] >= 0)         f[i][j][k] +=  f[i - 1][j - 1][k - w[j]]; }    }    return f[r][m][n];}int main(){    tot = getprm(1120);    while (scanf("%d%d", &n, &r), n | r)        printf("%dn", work());    return 0;}
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