HDU 1597 find the nth digit 水题

思路：n在$S_k$中，二分找到。

http://acm.hdu.edu.cn/showproblem.php?pid=1597

/*********************************************
    Problem : HDU 1597
    Author  : NMfloat
    InkTime (c) NM . All Rights Reserved .
********************************************/

#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cmath>
#include <ctime>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>

#define rep(i,a,b)  for(int i = (a) ; i <= (b) ; i ++)
#define rrep(i,a,b) for(int i = (b) ; i >= (a) ; i --)
#define repE(p,u) for(Edge * p = G[u].first ; p ; p = p -> next)
#define cls(a,x)   memset(a,x,sizeof(a))
#define eps 1e-8

using namespace std;

const int MOD = 1e9+7;
const int INF = 0x3f3f3f3f;
const int MAXN = 1e5+5;
const int MAXE = 2e5+5;

typedef long long LL;
typedef unsigned long long ULL;

int T,m,k;
LL n;

int fx[] = {0,1,-1,0,0};
int fy[] = {0,0,0,-1,1};

void input() {
    scanf("%lld",&n);
}

void solve() {
    LL left = 1;
    LL right = 100000;
    LL mid ;
    while(left < right) {
        mid = (left + right) >> 1;
        if(mid*(mid+1)/2 < n) left = mid + 1;
        else right = mid ;
    }
    left --;
    LL pos = n - left * (left + 1) / 2;
    printf("%lld\n",(pos-1)%9+1);
}

int main(void) {
    //freopen("a.in","r",stdin);
    scanf("%d",&T); while(T--) {
        input();
        solve();
    }
    return 0;
}