uva 1549 - Lattice Point(暴力)

题目链接：uva 1549 - Lattice Point

题目大意：给定圆半径，以原点为圆心，求园内有多少个整数点。

解题思路：首先坐标轴将圆分成4份，所以只要单独考虑每一块的个数乘4再加1即可（原点）

#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>using namespace std;const double pi = 4 * atan(1.0);typedef long long ll;ll solve (ll R) {    ll ret = 0;    ll r = R, M = R * R;    for (ll i = 0; i <= R; i++) {        while (r * r + i * i > M)            r--;        ret += r;    }    return 4 * ret + 1;}int main () {    ll n;    while (scanf("%lld", &n) == 1) {        printf("%lld\n%lld\n", n, solve(n));    }    return 0;}