求助，70分卡在1，3，4这几个点了

#include <bits/stdc++.h>
using namespace std;
#define limit (10000 + 5)//防止溢出
#define INF 0x3f3f3f3f
#define inf 0x3f3f3f3f3f
#define lowbit(i) i&(-i)//一步两步
#define EPS 1e-6
#define FASTIO  ios::sync_with_stdio(false);cin.tie(0);
#define ff(a) printf("%d\n",a );
#define pi(a,b) pair<a,b>
#define rep(i, a, b) for(int i = a; i <= b ; ++i)
#define per(i, a, b) for(int i = b ; i >= a ; --i)
#define mint(a,b,c) min(min(a,b), c)
#define MOD 998244353
#define FOPEN freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\data.txt", "rt", stdin)
typedef long long ll;
typedef unsigned long long ull;
ll read(){
    ll sign = 1, x = 0;char s = getchar();
    while(s > '9' || s < '0' ){if(s == '-')sign = -1;s = getchar();}
    while(s >= '0' && s <= '9'){x = x * 10 + s - '0';s = getchar();}
    return x * sign;
}//快读
void write(ll x){
    if(x < 0) putchar('-'),x = -x;
    if(x / 10) write(x / 10);
    putchar(x % 10 + '0');
}

int n,m,k,tot;
int a[limit];
double dp[limit][100 + 5];//做i道对j道的
int main() {
#ifdef LOCAL
    FOPEN;
#endif
    n = read(),m = read(), k = read();
    double p = 1.0 * m / 100;//概率
    double np = 1 - p;
    rep(i ,1,n){
        char c;
        scanf("%c" , &c);
        a[i] = c - '0';
    }
    if(!k && n > 50)
        return 0 * puts("1.000");
    dp[0][0] = 1.00;
    rep(i ,1, n){//从上一题过来然后写错
        dp[i][0] = dp[i - 1][0] * (a[i] ? np : p);//
    }
    rep(i ,1, n){
        rep(j ,1, i){
            if(!a[i])dp[i][j] = dp[i - 1][j] * p + dp[i - 1][j - 1] * np;//如果不一样就是要么上一题的时候做错了，
            else dp[i][j] = dp[i - 1][j] * np + dp[i - 1][j - 1] * p;
        }
    }
//    rep(i ,1, n){
//        rep(j ,1, i){
//            printf("at %d and %d we have%lf    ",i,j, dp[i][j]);
//        }
//        cout<<endl;
//    }
    double ans = 0.0000;
    per(i , k , n){
        ans += dp[n][i];
    }
    printf("%.3lF", ans);
    return 0;
}