codeforces 669B Little Artem and Grasshopper

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本文介绍了一个关于模拟蚂蚱跳跃路径的编程问题。通过输入不同方向和距离的数据，判断蚂蚱是否能跳出限定区域，实现无限跳跃还是有限跳跃。

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Little Artem found a grasshopper. He brought it to his house and constructed a jumping area for him.

The area looks like a strip of cells 1 × n. Each cell contains the direction for the next jump and the length of that jump. Grasshopper starts in the first cell and follows the instructions written on the cells. Grasshopper stops immediately if it jumps out of the strip. Now Artem wants to find out if this will ever happen.

Input

The first line of the input contains a single integer n (1 ≤ n ≤ 100 000) — length of the strip.

Next line contains a string of length n which consists of characters "<" and ">" only, that provide the direction of the jump from the corresponding cell. Next line contains n integers di (1 ≤ di ≤ 109) — the length of the jump from the i-th cell.

Output

Print "INFINITE" (without quotes) if grasshopper will continue his jumps forever. Otherwise print "FINITE" (without quotes).

        Examples
      

          input
        
2
><
1 2

          output
        
FINITE

          input
        
3
>><
2 1 1

          output
        
INFINITE

Note

In the first sample grasshopper starts from the first cell and jumps to the right on the next cell. When he is in the second cell he needs to jump two cells left so he will jump out of the strip.

Second sample grasshopper path is 1 - 3 - 2 - 3 - 2 - 3 and so on. The path is infinite.

题意：判断蚂蚱能不能跳出去，注意审清题，给出的i的方向和距离。然后模拟这个过程。

#include<cstdio>
#include<cstring>
const int max1=1e5+10;
int n,a[max1];
char str[max1];
int main()
{
    scanf("%d",&n);
    scanf("%s",str+1);
    int k=1;
    for(int i=1;i<=n;i++)
        scanf("%d",&a[i]);
    for(int i=1;i<=n;i++)
    {
        if(str[k]=='>')
            k+=a[k];
        else
            k-=a[k];
        if(k<1||k>n)
        {
            printf("FINITE\n");
            return 0;
        }
    }
    printf("INFINITE\n");
    return 0;
}