【CodeVS 1198】【NOIP 2012】国王游戏

http://codevs.cn/problem/1198/

推导一翻，排好序后，直接上高精度。

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int in() {
	int k = 0, fh = 1; char c = getchar();
	for(; c < '0' || c > '9'; c = getchar())
		if (c == '-') fh = -1;
	for(; c >= '0' && c <= '9'; c = getchar())
		k = (k << 3) + (k << 1) + c - '0';
	return k * fh;
}
 
struct node {
	int l, r, num;
	bool operator < (const node &A) const {
		return num < A.num;
	}
} a[1003];
int n, l, r;
 
struct Big {
	int num[50003], len;
	Big() {memset(num, 0, sizeof(num)); len = 0;}
	Big operator * (const int b) const {
		Big c;
		for(int i = 1; i <= len; ++i) {
			c.num[i] += num[i] * b;
			c.num[i + 1] += c.num[i] / 10;
			c.num[i] %= 10;
		}
		c.len = len;
		while (c.num[c.len + 1] != 0) {
			++c.len;
			c.num[c.len + 1] = c.num[c.len] / 10;
			c.num[c.len] %= 10;
		}
		return c;
	}
	Big operator / (const int b) const {
		int y = 0;
		Big c;
		for(int i = len; i >= 1; --i) {
			y = y * 10 + num[i];
			c.num[i] = y / b;
			y = y % b;
		}
		c.len = len;
		while (c.num[c.len] == 0 && c.len > 1) --c.len;
		return c;
	}
	bool operator < (const Big &b) const {
		if (len != b.len) return len < b.len;
		for(int i = len; i >= 1; --i)
			if (num[i] != b.num[i])
				return num[i] < b.num[i];
		return false;
	}
	void print() {
		for(int i = len; i >= 1; --i)
			putchar('0' + num[i]);
		puts("");
	}
};
 
int main() {
	n = in(); l = in(); r = in();
	for(int i = 1; i <= n; ++i)
		a[i].l = in(), a[i].r = in(), a[i].num = a[i].l * a[i].r;
	sort(a + 1, a + n + 1);
	Big t, ans, cal;
	while (l > 0) {
		t.num[++t.len] = l % 10;
		l /= 10;
	}
	ans.len = -1;
	for(int i = 1; i <= n; ++i) {
		cal = t / a[i].r;
		if (ans < cal) ans = cal;
		t = t * a[i].l;
	}
	ans.print();
	return 0;
}

QwQ