HDU 4345 Permutation dp

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#include <cstring>#include <vector>#include <list>#include <map>#include <set>#include <deque>#include <stack>#include <bitset>#include <algorithm>#include <functional>#include <numeric>#include <utility>#include <sstream>#include <iostream>#include <iomanip>#include <cstdio>#include <cmath>#include <cstdlib>#include <ctime>#include <memory.h>#include <cassert>using namespace std;typedef long long ll;const int N = 185;const int M = 1000 + 1;bool pri(int x) {if (x == 2)return true;else if (x%2==0)return false;for (int i = 3; i * i <= x; i += 2)if (x%i==0)return false;return true;}int prime[N], idx = 0;ll ans[M], d[N][M];int main() {int v;ll sum;for (int i = 2; i <= 1000; ++i)if (pri(i))prime[idx++] = i;memset(d, 0, sizeof d);d[0][0] = 1;for (int i = 0; i < idx; ++i) {v = prime[i];while (v < M) {for (int j = v; j < M; ++j)d[i+1][j] += d[i][j - v];v = v * prime[i];}for (int j = 0; j < M; ++j)d[i+1][j] += d[i][j];}ans[0] = d[idx][0];for (int i = 1; i < M; ++i)ans[i] = ans[i - 1] + d[idx][i];ans[0] = 0;int n;while (~scanf("%d", &n)) {printf("%I64d\n", ans[n]);}return 0;}

HDU 4345 Permutation dp