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D. Multiplication Table
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Bizon the Champion isn't just charming, he also is very smart.
While some of us were learning the multiplication table, Bizon the Champion had fun in his own manner. Bizon the Champion painted ann × m multiplication table, where the element on the intersection of the i-th row and j-th column equals i·j (the rows and columns of the table are numbered starting from 1). Then he was asked: what number in the table is the k-th largest number? Bizon the Champion always answered correctly and immediately. Can you repeat his success?
Consider the given multiplication table. If you write out all n·m numbers from the table in the non-decreasing order, then the k-th number you write out is called the k-th largest number.
Input
The single line contains integers n, m and k (1 ≤ n, m ≤ 5·105; 1 ≤ k ≤ n·m).
Output
Print the k-th largest number in a n × m multiplication table.
Examples
input
2 2 2
output
2
input
2 3 4
output
3
input
1 10 5
output
5
Note
A 2 × 3 multiplication table looks like this:
1 2 3
2 4 6
从 1 到 n*m 二分找结果。注意数据类型。
代码如下:
#include <cstdio>
#include <algorithm>
using namespace std;
__int64 n,m,k;
bool check(__int64 x)
{
__int64 sum = 0;
for (int i = 1 ; i <= n ; i++)
{
sum += min(m , x / i);
if (sum >= k)
return true;
}
return false;
}
int main()
{
scanf ("%I64d %I64d %I64d",&n,&m,&k);
__int64 l,r,mid;
l = 1;
r = n*m;
while (r >= l)
{
mid = (l + r) / 2;
if (check(mid))
r = mid - 1;
else
l = mid + 1;
}
printf ("%I64d\n",l);
return 0;
}