Problem: Find a value from a rotational sorted array.
Solution Hint: binary search.
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#include <stdio.h> int arr[100010]; int bin_search(int lw,int hi,int v) { if(v<arr[lw] || v>arr[hi]) return 0; int mid; while(lw<=hi) { mid=(lw+hi)/2; if(arr[mid]==v) { printf("%d\n",mid); return 1; } else if(arr[mid]<v) lw=mid+1; else if(arr[mid]>v) hi=mid; } return 0; } int main() { //code int t,i,j,n,val,a,idx; int f=0; int lw,mid,hi; scanf("%d",&t); while(t--) { scanf("%d",&n); val=100010; f=0; for( i=0;i<n;i++) { scanf("%d",&arr[i]); if(arr[i]<val) { val=arr[i]; idx=i; } } scanf("%d",&a); lw=idx;hi=(idx+n-1)%n; f=bin_search(0,hi,a); if(f==0) f=bin_search(lw,n-1,a); if(f==0) printf("-1\n"); } return 0; } |