Submission #1481614

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define int long long

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,int> plli;
typedef pair<int,pii> pipii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<pii> vpii;

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n);i>0;i--)
#define rrep2(i,a,b) for (int i=(a);i>b;i--)
#define pb push_back
#define fi first
#define se second
#define all(a) (a).begin(),(a).end()

const ll mod = 1e9 + 7;
const ll INF = 1<<30;
const int dx4[4] = {1, 0, -1, 0};
const int dy4[4] = {0, 1, 0, -1};
const int dx8[8] = {1, 1, 1, 0, 0, -1, -1, -1};
const int dy8[8] = {0, 1, -1, 1, -1, 0, 1, -1};
const double pi = 3.141592653589793;

int n, m;
long double p[105];
long double dp[105][205][105];

signed main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> n >> m;
    rep(i, n) {cin >> p[i]; p[i] /= 100.0;}
    dp[1][1][1] = 1.0;
    rep2(i, 1, n)rep(j, m + 1)rep2(k, 1, n) {
        if (j < k) break;
        if (j == k) {
            if (j + 1 > m) dp[i + 1][m][k] += dp[i][j][k] * p[i];
            else dp[i + 1][j + 1][k + 1] += dp[i][j][k] * p[i];
        }
        else {
            dp[i + 1][j][k + 1] += dp[i][j][k] * p[i];
        }
        if (j + 2 > m) dp[i + 1][j][k] += dp[i][j][k] * (1.0 - p[i]);
        else dp[i + 1][j + 2][k + 1] += dp[i][j][k] * (1.0 - p[i]);
    }
    long double ans = 0.0;
    rep(j, m + 1)rep(k, n + 1) ans += dp[n][j][k] * (long double)(m - k);
    cout << fixed << setprecision(10) << ans << endl;
}

Submission Info

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