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Lesson: 44
Problem: 2990
Title: Simple Task
Difficulty Level: 2.0
Date: MAR 03, 2009
Site: http://acm.tju.edu.cn/toj/showp2990.html

Very good one for beginners. Try to figure out the logic from my code to solve this problem.



#include<stdio.h>
#define maxn 20001
#define CON 10000


int F[maxn];

void Cal() {
	int m, res = 0, n, need;
	scanf("%d",&n);
	for(int i = 0; i<n; i++) {
		scanf("%d",&m);
		need = 0 - m + CON;
		res += F[need];
	}
	printf("%d\n",res);
	for(n = 0; n<maxn; n++) F[n] = 0; 

}

int main() {
	int kase, n, m;
	freopen("h.txt","r",stdin);
	scanf("%d",&kase);
	while(kase--) {
		scanf("%d",&n);
		while(n--) {
			scanf("%d",&m);
			m += CON;
			F[m] ++;
		}
		Cal();
	}
	return 0;
}
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