It can be done with Segment Trees (with the same complexity). Using segment tree from here.

struct segment_tree {
    int t[2*maxN];
    void build() {
        for (int i=n-1;i>0;--i)
            t[i]=min(t[i<<1],t[i<<1|1]);
    }
    int query(int l,int r) {
        int minV=inf;
        for (l+=n,r+=n;l<r;l>>=1,r>>=1) {
            if (l&1)  minV=min(minV,t[l++]);
            if (r&1)  minV=min(minV,t[--r]);
        }
        return minV;
    }
 
}

With BIT you can only get the minimum value on the interval (1, r)

Thanks all :D

I solved this simple problem with this code, and the runtime was pretty good.

can any one please tell me the complexity of my code.

I didn't thought it would pass the time limit, but indeed it was pretty fast.