vj467A--George and Accommodation

问题来源

vj467A

问题描述

George has recently entered the BSUCP (Berland State University for Cool Programmers). George has a friend Alex who has also entered the university. Now they are moving into a dormitory.

George and Alex want to live in the same room. The dormitory has n rooms in total. At the moment the i-th room has pi people living in it and the room can accommodate qi people in total (pi ≤ qi). Your task is to count how many rooms has free place for both George and Alex.

输入

The first line contains a single integer n (1 ≤ n ≤ 100) — the number of rooms.

The i-th of the next n lines contains two integers pi and qi (0 ≤ pi ≤ qi ≤ 100) — the number of people who already live in the i-th room and the room’s capacity.

输出

Print a single integer — the number of rooms where George and Alex can move in.

例子

AC的代码

#include<iostream>
using namespace std;
int main()
{int i,t,k,s=0;cin>>i;while(i){cin>>t;cin>>k;if((k-t)>=2)s++;i--;}
cout<<s;}

解题思路

用i保存示例数，i次循环分别输入已有人数和可住人数，若有一个房间可住人数减去已有人数大于等于2，则s加一，循环结束输出s，则为可住房间数。