【杂题】 codeforces 448D Multiplication Table

简单二分。。比赛时没想到。。

#include <iostream>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <climits>  
#include <cstdlib>
#include <cmath>
#define maxn 1000005
#define eps 1e-10
#define mod 1000000009
#define INF 99999999  
#define lowbit(x) (x&(-x))  
#define lson o<<1, L, mid  
#define rson o<<1 | 1, mid+1, R  
typedef long long LL;
using namespace std;

int main(void)
{
	LL n, m, k, top, mid, bot, i, cnt, ans;
	scanf("%I64d%I64d%I64d", &n, &m, &k);
	bot = 1, top = n*m;
	while(bot<=top) {
		mid = (bot+top)>>1, cnt = 0;
		for(i = 1; i <= n; i++)
			cnt += min(mid/i, m);
		if(cnt >= k) top = mid-1, ans = mid;
		else bot = mid+1;
	}
	printf("%I64d\n", ans);
	return 0;
}