mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
110 lines
2.5 KiB
C++
110 lines
2.5 KiB
C++
#include <iostream>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <queue>
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#include <algorithm>
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#include <math.h>
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using namespace std;
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#define M 205
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#define eps 1e-8
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int equ, var;
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double a[M][M], x[M];
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int Gauss ()
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{
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int i, j, k, col, max_r;
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for (k = 0, col = 0; k < equ && col < var; k++, col++)
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{
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max_r = k;
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for (i = k+1; i < equ; i++)
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if (fabs (a[i][col]) > fabs (a[max_r][col]))
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max_r = i;
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if (k != max_r)
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{
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for (j = col; j < var; j++)
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swap (a[k][j], a[max_r][j]);
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swap (x[k], x[max_r]);
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}
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x[k] /= a[k][col];
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for (j = col+1; j < var; j++) a[k][j] /= a[k][col];
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a[k][col] = 1;
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for (i = 0; i < equ; i++) if (i != k)
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{
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x[i] -= x[k] * a[i][k];
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for (j = col+1; j < var; j++) a[i][j] -= a[k][j] * a[i][col];
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a[i][col] = 0;
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}
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}
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return 1;
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}
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int has[M], vis[M], k, e, n, m;
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double p[M], sum;
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int bfs (int u)
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{
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memset (has, -1, sizeof(has));
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memset (a, 0, sizeof(a));
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memset (vis, 0, sizeof(vis));
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int v, i, flg = 0;
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queue<int> q;
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q.push (u);
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k = 0;
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has[u] = k++;
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while (!q.empty ())
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{
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u = q.front ();
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q.pop ();
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if (vis[u]) continue;
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vis[u] = 1;
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if (u == e || u == n-e)
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{
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a[has[u]][has[u]] = 1;
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x[has[u]] = 0;
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flg = 1;
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continue;
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}
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a[has[u]][has[u]] = 1;
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x[has[u]] = sum;
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for (i = 1; i <= m; i++)
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{
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if (fabs (p[i]) < eps) continue;
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v = (u + i) % n;
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if (has[v] == -1) has[v] = k++;
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a[has[u]][has[v]] -= p[i];
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q.push (v);
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}
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}
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return flg;
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}
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int main()
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{
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int t, s, d, i;
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scanf ("%d", &t);
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while (t--)
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{
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scanf ("%d%d%d%d%d", &n, &m, &e, &s, &d);
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n = 2*(n-1);
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sum = 0;
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for (i = 1; i <= m; i++)
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{
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scanf ("%lf", p+i);
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p[i] = p[i] / 100;
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sum += p[i] * i;
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}
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if (s == e)
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{
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puts ("0.00");
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continue;
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}
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if (d > 0) s = (n - s) % n;
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if (!bfs (s))
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{
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puts ("Impossible !");
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continue;
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}
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equ = var = k;
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Gauss ();
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printf ("%.2f\n", x[has[s]]);
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}
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return 0;
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}
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