24 lines
586 B
C++
24 lines
586 B
C++
#include <bits/stdc++.h>
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using namespace std;
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#define int long long
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#define endl "\n"
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// C(n,3)计算公式
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int C(int n) {
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return n * (n - 1) * (n - 2) / (3 * 2 * 1);
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}
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signed main() {
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int n, m;
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cin >> n >> m; // 行数,列数
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n++, m++; // 将格子数转换成格点数,n->n+1,m->m+1
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int res = C(n * m) - n * C(m) - m * C(n);
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// 枚举所有高为i,宽为j的线段AB
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for (int i = 1; i <= n; i++)
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for (int j = 1; j <= m; j++)
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res -= 2 * (__gcd(i, j) - 1) * (n - i) * (m - j);
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printf("%lld\n", res);
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}
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