8.14-T2捕老鼠（cat）

#include<bits/stdc++.h>
using namespace std;

inline int read()
{
    int sum = 0,p = 1;
    char ch = getchar();
    while(ch < ‘0‘ || ch > ‘9‘)
    {
        if(ch == ‘-‘)
            p = -1;
        ch = getchar();
    }
    while(ch >= ‘0‘ && ch <= ‘9‘)
    {
        (sum *= 10) += ch - ‘0‘;
        ch = getchar();
    }
    return sum * p;
}

const int N = 5e5 + 5;
int n,ans;
struct edge
{
    int l,r;
} e[N];

int main()
{
    freopen("cat.in","r",stdin);
    freopen("cat.out","w",stdout);
    n = read();
    for(int i = 1; i <= n; i++)
    {
        int a = read();
        e[i].l = max(0,i - a);
        e[i].r = min(n,i + a);
    }
    int far = 0,now = 1,mid;
    while(now <= n)
    {
        far = 0;
        for(int i = 1;i <= n;i++)
        {
            if(e[i].l <= now && e[i].r >= now)
                if(far < e[i].r)
                    far = e[i].r;
        }
        now = far + 1;
        ans++;
    }
    printf("%d\n",ans);
    return 0;
}