138_二分搜索 （lower_bound)

//
//  138_lower bound.cpp
//  changlle
//
//  Created by user on 1/8/16.
//  Copyright (c) 2016 user. All rights reserved.
//

#include <iostream>
using namespace std;

int n=5;
int a[5]={2,3,3,5,6};
int k=3;

void solve() {

int lb=-1,ub=n;

while (ub-lb>1){
int mid =(lb+ub)/2;

if(a[mid]>=k)
ub=mid;
else
lb=mid;

}

cout<<ub<<endl;

}

int main() {

solve();

return 0;

}