SGU - 133 - Border （简单统计）

133. Border

time limit per test: 0.25 sec. 
memory limit per test: 4096 KB

Along the border between states A and B there are N defence outposts. For every outpost k, the interval [A_k,B_k] which is guarded by it is known. Because of financial reasons, the president of country A decided that some of the outposts should be abandoned. In fact, all the redundant outposts will be abandoned. An outpost i is redundant if there exists some outpost j such that A_j<A_i and B_i<B_j. Your task is to find the number of redundant outposts.

Input

The first line of the input will contain the integer number N (1<=N<=16 000). N lines will follow, each of them containing 2 integers: A_k and B_k (0<= A_k < B_k <= 2 000 000 000), separated by blanks. All the numbers A_k will be different. All the numbers B_k will be different.

Output

You should print the number of redundant outposts.

Sample Input

50 102 93 81 156 11

Sample Output

3

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Author: Mugurel Ionut AndreicaResource: SSU::Online Contester Fall Contest #2Date: Fall 2002

思路：将整数对按照第一个值升序排列，然后往后遍历，每次的第二个值如果比之前的第二个值中的最大值小，则ans++，注意不要加EOF，会PE

AC代码：

#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>using namespace std;struct node {int x, y;}a[16005];int N;bool cmp(node a, node b) {return a.x < b.x;}int main() {scanf("%d", &N);for(int i = 0; i < N; i++) {scanf("%d %d", &a[i].x, &a[i].y);}sort(a, a + N, cmp);int ans = 0;int MAX = a[0].y;for(int i = 1; i < N; i++) {if(a[i].y < MAX) ans ++;else MAX = a[i].y;}printf("%d\n", ans);return 0;}