【杂题】 HDOJ 4961 Boring Sum

预处理约数就可以了。。

#include <iostream>  #include <queue>  #include <stack>  #include <map>  #include <set>  #include <bitset>  #include <cstdio>  #include <algorithm>  #include <cstring>  #include <climits>  #include <cstdlib>#include <cmath>#include <time.h>#define maxn 100005#define maxm 40005#define eps 1e-10#define mod 998244353#define INF 999999999#define lowbit(x) (x&(-x))#define mp mark_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid  #define rson o<<1 | 1, mid+1, R//#pragma comment (linker,"/STACK:102400000,102400000")typedef long long LL;//typedef int LL;using namespace std;LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}// headvector<int> g[maxn];int a[maxn], next[maxn];int b[maxn], c[maxn];int n;void init(void){int tmp;for(int i = 1; i <= 100000; i++) {tmp = sqrt(i);for(int j = 1; j <= tmp; j++)if(i%j == 0) {g[i].push_back(j);if(j != i/j)g[i].push_back(i/j);}}}void work(void){LL ans = 0;memset(next, -1, sizeof next);for(int i = 1; i <= n; i++) {if(next[a[i]] == -1) b[i] = a[i];else b[i] = a[next[a[i]]];int d = g[a[i]].size();for(int j = 0; j < d; j++) next[g[a[i]][j]] = i;}memset(next, -1, sizeof next);for(int i = n; i >= 1; i--) {if(next[a[i]] == -1) c[i] = a[i];else c[i] = a[next[a[i]]];int d = g[a[i]].size();for(int j = 0; j < d; j++) next[g[a[i]][j]] = i;}for(int i = 1; i <= n; i++) ans += (LL)b[i]*c[i];printf("%I64d\n", ans);}int main(void){init()while(scanf("%d", &n), n != 0) {for(int i = 1; i <= n; i++) scanf(a[i]);//scanf("%d", &a[i]);work();}return 0;}