54 lines
1.4 KiB
C++
54 lines
1.4 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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const int N = 5e6 + 10;
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struct Node {
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int c, d, sum;
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bool operator<(const Node &t) const {
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if (sum != t.sum) return sum < t.sum;
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if (c != t.c) return c < t.c;
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return d < t.d;
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}
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} f[N];
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int n;
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int idx;
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int main() {
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scanf("%d", &n);
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// C预处理出 c^2+d^2
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for (int c = 0; c * c <= n; c++)
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for (int d = c; c * c + d * d <= n; d++)
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f[idx++] = {c, d, c * c + d * d};
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//结构体排序
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sort(f, f + idx);
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//枚举a^2+b^2
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for (int a = 0; a * a <= n; a++) {
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for (int b = a; a * a + b * b <= n; b++) {
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int t = n - a * a - b * b;
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//手写二分模板,左闭右开
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// STL二分缺点:
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// 1、常数较大,速度慢
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// 2、对于结构体二分，需要构造空的Struct,还需要有一些玄学的赋零操作，不推荐
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//结论：全面采用手写二分办法，忘记STL的二分写法
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int l = 0, r = idx;
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while (l < r) {
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int mid = (l + r) >> 1;
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if (f[mid].sum >= t)
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r = mid;
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else
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l = mid + 1;
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}
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if (f[l].sum == t) {
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cout << a << ' ' << b << ' ' << f[l].c << ' ' << f[l].d << ' ' << endl;
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exit(0);
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}
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}
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}
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return 0;
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} |