1083 whether there is equal difference PAT (Basic Level)

Topic links:

https://pintia.cn/problem-sets/994805260223102976/problems/994805260780945408

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analysis:

The number of times a difference is present in the array corresponding to a position, and from a [n-1] is greater than a start determination, if greater than 1, the number of landmarks and the output until a [0] end use while ( n--) just achieved.

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AC Code:

 1 #include<stdio.h>
 2 
 3 int main(void)
 4 {
 5     int n=0,m=0,i=0,a[10008]={0};
 6     scanf("%d",&n);
 7     for(i=1;i<=n;i++)
 8     {
 9         scanf("%d",&m);
10         ++a[m-i<0?i-m:m-i];
11     }
12     while(n--)
13         if(a[n]>1)
14             printf("%d %d\n",n,a[n]);
15     return 0;
16 }