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int ans =0;//getans for(int i=0;i<=cash;i++) ans=max(ans,f[i]); printf(\,ans); } return0; }

多重背包通用模板（单调队列）

int f[N];

int va[N], vb[N];//MAX_V

void pack(int V,int v,int w,int n){ if(n==0||v==0)return; if(n==1){//01背包

for(int i=V;i>=v;--i)

f[i]=max(f[i],f[i-v]+w); return; }

if(n*v>=V-v+1){//多重背包(n >= V / v) for(int i=v;i<=V;++i)

f[i]=max(f[i],f[i-v]+w); return; }

for(int j =0; j < v ;++j ){ int*pb = va,*pe = va -1; int*qb = vb,*qe = vb -1;

for(int k=j,i=0;k<=V;k+=v,++i){ if(pe==pb+n){ if(*pb ==*qb)++qb; ++pb; }

int tt = f[k]- i * w; *++pe = tt;

while(qe>=qb&&*qe

f[k]=*qb + i * w; }

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} }

//主程序调用

memset(f,0,sizeof(f));//pack for(int i=1;i<=n;i++)

pack(cash,a[i].v,a[i].w,a[i].n); int ans =0;//getAns

for(int i=0;i<=cash;i++) ans=max(ans,f[i]); printf(\,ans);

//Meisell-Lehmer //G++ 218ms 43252k #include #include using namespace std; #define LL long long const int N = 5e6 + 2; bool np[N];

int prime[N], pi[N]; int getprime() {

int cnt = 0;

np[0] = np[1] = true; pi[0] = pi[1] = 0;

for(int i = 2; i< N; ++i) {

if(!np[i]) prime[++cnt] = i; pi[i] = cnt;

for(int j = 1; j<= cnt&& i * prime[j] < N; ++j) {

np[i * prime[j]] = true; if(i % prime[j] == 0) break; } }

return cnt; }

const int M = 7;

const int PM = 2 * 3 * 5 * 7 * 11 * 13 * 17; int phi[PM + 1][M + 1], sz[M + 1]; void init() {

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getprime(); sz[0] = 1;

for(int i = 0; i<= PM; ++i) phi[i][0] = i; for(int i = 1; i<= M; ++i) {

sz[i] = prime[i] * sz[i - 1];

for(int j = 1; j<= PM; ++j) phi[j][i] = phi[j][i - 1] - phi[j / prime[i]][i - 1]; } }

int sqrt2(LL x) {

LL r = (LL)sqrt(x - 0.1); while(r * r<= x) ++r; return int(r - 1); }

int sqrt3(LL x) {

LL r = (LL)cbrt(x - 0.1); while(r * r * r<= x) ++r; return int(r - 1); }

LL getphi(LL x, int s) {

if(s == 0) return x;

if(s<= M) return phi[x % sz[s]][s] + (x / sz[s]) * phi[sz[s]][s]; if(x<= prime[s]*prime[s]) return pi[x] - s + 1; if(x<= prime[s]*prime[s]*prime[s] && x< N) {

int s2x = pi[sqrt2(x)];

LL ans = pi[x] - (s2x + s - 2) * (s2x - s + 1) / 2; for(int i = s + 1; i<= s2x; ++i) ans += pi[x / prime[i]]; return ans; }

return getphi(x, s - 1) - getphi(x / prime[s], s - 1); }

LL getpi(LL x) {

if(x< N) return pi[x];

LL ans = getphi(x, pi[sqrt3(x)]) + pi[sqrt3(x)] - 1;

for(int i = pi[sqrt3(x)] + 1, ed = pi[sqrt2(x)]; i<= ed; ++i) ans -= getpi(x / prime[i]) - i + 1;

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return ans; }

LL lehmer_pi(LL x) {

if(x< N) return pi[x];

int a = (int)lehmer_pi(sqrt2(sqrt2(x))); int b = (int)lehmer_pi(sqrt2(x)); int c = (int)lehmer_pi(sqrt3(x));

LL sum = getphi(x, a) +(LL)(b + a - 2) * (b - a + 1) / 2; for (int i = a + 1; i<= b; i++) {

LL w = x / prime[i]; sum -= lehmer_pi(w); if (i> c) continue;

LL lim = lehmer_pi(sqrt2(w));

for (int j = i; j<= lim; j++) sum -= lehmer_pi(w / prime[j]) - (j - 1); }

return sum; }

int main() {

init(); LL n;

while(~scanf(\,&n)) {

printf(\,lehmer_pi(n)); }

return 0; }