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https://github.com/Kiritow/OJ-Problems-Source.git
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67 lines
1.3 KiB
C++
67 lines
1.3 KiB
C++
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#include <iostream>
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#include <cstdio>
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#include <cmath>
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using namespace std;
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int const maxn = 51 + 51 * 50 / 2;
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int n, m;
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long long dp[55][55];
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bool triangle[maxn];
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long long gcd(long long a, long long b)
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{
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if(b)
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return gcd(b, a % b);
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return a;
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}
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int main()
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{
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scanf("%d %d", &n, &m);
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char s[5];
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int index = 1;
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for(int i = 1; i <= n; i++)
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{
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for(int j = 1; j <= i; j++)
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{
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scanf("%s", s);
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if(s[0] == '*')
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triangle[index++] = true;
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else
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triangle[index++] = false;
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}
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}
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dp[1][1] = 1;
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for(int i = 1; i <= n; i++)
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dp[1][1] <<= 1;
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for(int i = 1; i <= n; i++)
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{
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int id = i * (i - 1) / 2;
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for(int j = 1; j <= i; j++)
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{
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if(triangle[id + j])
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{
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dp[i+1][j] += dp[i][j] >> 1;
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dp[i+1][j+1] += dp[i][j] >> 1;
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}
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else
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{
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dp[i+2][j+1] += dp[i][j];
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}
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}
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}
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long long ans1 = dp[n+1][m+1];
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long long ans2 = 0;
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for(int i = 1; i <= n + 1; i++)
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ans2 += dp[n+1][i];
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long long k = gcd(ans1,ans2);
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if(ans1 == 0)
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{
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ans2 = 1;
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k = 1;
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}
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printf("%lld/%lld\n", ans1 / k, ans2 / k);
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}
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