为什么我的字符串过不去啊?求大佬指错!

#define N 200010
#define LL long long
using namespace std;

int  main()
{
    LL n, m;
    cin >> n >> m;
    getchar();
    string s;
    cin >> s;
    LL a[N];
    for(int i = 0; i < n; i++)
        cin >> a[i];
    int id = 0;
    int xb[N];
    bool jd = 0;
    for(int i = 0; i < n; i++)
    {
        if(s[i] == s[i+1])
        {
            for(int ic = i; ic < n; ic++)
                if(s[ic] != s[ic+1] && s[ic] < s[ic+1])
                {
                    jd = 1;
                    break;
                }
        }
        if( jd || (s[i] < s[i+1] && m - a[i] >= 0))
        {
            xb[id++] = i;
            m -= a[i];
            jd = 0;
        }
    }
    
    for(int i = 0; i < id; i++)
    {
        s.insert(s.begin()+xb[i]+i, s[i+xb[i]]);
    }
    cout << s << endl;
    return 0;
} js