Pagini recente » Monitorul de evaluare | Cod sursa (job #2062175)
#include <bits/stdc++.h>
using namespace std;
ifstream fin("nrtri.in");
ofstream gout("nrtri.out");
int a[850];
int n;
int cautare_binara(int a[], int st, int dr, int val)
{
int top = st - 1;
int bot = st - 1;
cerr << bot << " " << top << " ";
while(st <= dr) {
int mid = st + (dr - st) / 2;
if(val >= a[mid]) {
top = mid;
st = mid + 1;
}
else {
dr = mid - 1;
}
}
cerr << bot << " " << top << '\n';
return top - bot;
}
int main()
{
fin >> n;
for(int i = 1; i <= n; ++i) fin >> a[i];
sort(a + 1, a + n + 1);
//for(int i = 1; i <= n; ++i) gout << a[i] << " ";
//gout << '\n';
int ans = 0;
for(int i = 1; i < n; ++i) {
for(int j = i + 1; j <= n; ++j) {
int suma = a[i] + a[j];
int pos = cautare_binara(a, j + 1, n, suma);
ans += pos;;
}
}
gout << ans;
return 0;
}