The Number of Products

https://vjudge.net/contest/365698#problem/J

l[i]表示以a[i]为右端点的为负数的情况，r[i]表示为整数。

转移就是这样：
if(a[i]<0){
l[i]=r[i-1]+1;
r[i]=l[i-1];
}
else{
l[i]=l[i-1];
r[i]=r[i-1]+1;
}

 

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#define inf 2147483647
#define N 1000010
#define p(a) putchar(a)
#define For(i,a,b) for(long long i=a;i<=b;++i)

using namespace std;
long long T;
long long n,ans;
long long a[N],l[N],r[N],x,y;

void in(long long &x){
    long long y=1;char c=getchar();x=0;
    while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}
    while(c<='9'&&c>='0'){ x=(x<<1)+(x<<3)+c-'0';c=getchar();}
    x*=y;
}
void o(long long x){
    if(x<0){p('-');x=-x;}
    if(x>9)o(x/10);
    p(x%10+'0');
}

signed main(){
    in(n);
    For(i,1,n) in(a[i]);
    For(i,1,n){
        if(a[i]<0){
            l[i]=r[i-1]+1;
            r[i]=l[i-1];
        }
        else{
            l[i]=l[i-1];
            r[i]=r[i-1]+1;
        }
    }
    For(i,1,n){
        x+=l[i];
        y+=r[i];
    }
    o(x);p(' ');o(y);
    return 0;
}