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https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
50 lines
1.3 KiB
C++
50 lines
1.3 KiB
C++
#include <cstdio>
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typedef long long LL;
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const int maxn = 100010, mod = 1000000007, inv2 = 500000004;
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int t, n, pw1[maxn], pw2[maxn], x, y, pre1x, pre1y, pre2x, pre2y, ans;
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int mod_add(int x, int y)
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{
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x += y;
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if(x >= mod)
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x -= mod;
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return x;
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}
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int mod_sub(int x, int y)
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{
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x -= y;
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if(x < 0)
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x += mod;
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return x;
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}
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int det(int x1, int y1, int x2, int y2)
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{
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return mod_sub((LL)x1 * y2 % mod, (LL)x2 * y1 % mod);
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}
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int main()
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{
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scanf("%d", &t);
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pw1[0] = 1;
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for(int i = 1; i < maxn; ++i)
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pw1[i] = (LL)pw1[i - 1] * 2 % mod;
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pw2[0] = 1;
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for(int i = 1; i < maxn; ++i)
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pw2[i] = (LL)pw2[i - 1] * inv2 % mod;
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while(t--)
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{
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scanf("%d", &n);
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pre1x = pre1y = pre2x = pre2y = ans = 0;
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for(int i = 1; i <= n; ++i)
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{
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scanf("%d%d", &x, &y);
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ans = mod_add(ans, (LL)pw1[i - 1] * det(x, y, pre2x, pre2y) % mod);
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ans = mod_add(ans, (LL)(i == n ? inv2 : pw1[n - i - 1]) * det(pre1x, pre1y, x, y) % mod);
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pre1x = mod_add(pre1x, (LL)x * pw1[i] % mod);
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pre1y = mod_add(pre1y, (LL)y * pw1[i] % mod);
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pre2x = mod_add(pre2x, (LL)x * pw2[i] % mod);
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pre2y = mod_add(pre2y, (LL)y * pw2[i] % mod);
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}
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printf("%d\n", ans);
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}
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return 0;
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}
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