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Submission #860545

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```#include <iostream>
using namespace std;

#define MAX_N 100000

int tab[40][MAX_N];

// mid日でaからbまで行けるか
bool C(int a, int b, int mid){
int pos = a;
int cnt = 0;
while(mid != 0){
if(mid & 1){
pos = tab[cnt][pos];
}
mid >>= 1;
cnt++;
}
if(pos >= b) return true;
else return false;
}

int solve(int a, int b){
if(a > b) swap(a, b);

int ub = 100000;
int lb = 0;
while(ub - lb > 1){
int mid = lb + (ub - lb) / 2;
if(C(a, b, mid)) ub = mid;
else lb = mid;
}
return ub;
}

int main(){
cin.tie(0);
ios::sync_with_stdio(false);

int N, L, Q;
int x[MAX_N];

cin >> N;
for(int i=0; i<N; i++) cin >> x[i];
cin >> L >> Q;

int y[MAX_N];

for(int i=0; i<N; i++){
tab[0][i]  = upper_bound(x, x+N, x[i]+L) - x - 1;
}

for(int k=0; k<40; k++){
for(int i=0; i<N; i++){
tab[k+1][i] = tab[k][min(N-1, tab[k][i])];
}
}

for(int i=0; i<Q; i++){
int a, b;
cin >> a >> b;
a--; b--;
cout << solve(a, b) << endl;
}

return 0;
}
```

#### Submission Info

Submission Time 2016-08-31 13:40:04+0900 E - Tak and Hotels suzume C++14 (GCC 5.4.1) 0 1055 Byte CE

#### Compile Error

```./Main.cpp: In function ‘int main()’:
./Main.cpp:52:42: error: ‘upper_bound’ was not declared in this scope
tab[0][i]  = upper_bound(x, x+N, x[i]+L) - x - 1;
^
```