#include<bits/stdc++.h>

using namespace std;

const int INF = int(1e9);

struct segTree
{
    int n;
    bool mx;
    vector<int> t;

    void fix(int v)
    {
        t[v] = (mx ? max(t[v * 2 + 1], t[v * 2 + 2]) : min(t[v * 2 + 1], t[v * 2 + 2]));
    }

    void build(int v, int l, int r)
    {
        if(l == r - 1)
            t[v] = (mx ? -INF : INF);
        else
        {
            int m = (l + r) / 2;
            build(v * 2 + 1, l, m);
            build(v * 2 + 2, m, r);
            fix(v);
        }
    }

    void upd(int v, int l, int r, int pos, int val)
    {
        if(l == r - 1)
            t[v] = (mx ? max(t[v], val) : min(t[v], val));
        else
        {
            int m = (l + r) / 2;
            if(pos < m)
                upd(v * 2 + 1, l, m, pos, val);
            else
                upd(v * 2 + 2, m, r, pos, val);
            fix(v);
        }
    }

    int get(int v, int l, int r, int L, int R)
    {
        if(L >= R)
            return (mx ? -INF : INF);
        if(l == L && r == R)
            return t[v];
        int m = (l + r) / 2;
        int lf = get(v * 2 + 1, l, m, L, min(R, m));
        int rg = get(v * 2 + 2, m, r, max(m, L), R);
        return (mx ? max(lf, rg) : min(lf, rg));
    }

    void upd(int pos, int val)
    {
        upd(0, 0, n, pos, val);
    }

    int get(int L, int R)
    {
        return get(0, 0, n, L, R);
    }

    void build()
    {
        return build(0, 0, n);
    }

    segTree() {};
    segTree(int n, bool mx) : n(n), mx(mx)
    {
        t.resize(4 * n);
    }
};

int main()
{
    int t;
    scanf("%d", &t);
    for(int _ = 0; _ < t; _++)
    {
        int n;
        scanf("%d", &n);
        vector<int> p(n);
        for(int i = 0; i < n; i++)
            scanf("%d", &p[i]);
        vector<int> dp(n + 1, -INF);
        vector<int> par(n + 1, -2);
        dp[0] = 0;
        par[0] = -1;
        vector<int> lf(n), rg(n);
        for(int i = 0; i < n; i++)
        {
            lf[i] = max(1, i - p[i] + 1);
            rg[i] = min(n, i + p[i] + 1);
        }
        segTree sn(n + 1, false);
        segTree sx(n, true);
        sn.build();
        sx.build();
        for(int i = 0; i < n; i++)
            sx.upd(i, rg[i]);
        sn.upd(0, 0);
        for(int i = 1; i <= n; i++)
        {
            int j = i - 1;
            int k = lf[j] - 1;

            int m = sn.get(k, n + 1);
            if(m != INF)
            {
                int nval = max(sx.get(m, i - 1), i - 1);
                if(nval > dp[i])
                {
                    dp[i] = nval;
                    par[i] = m;
                }
            }
            if(dp[j] >= i && max(dp[j], rg[j]) > dp[i])
            {
                dp[i] = max(dp[j], rg[j]);
                par[i] = -1;
            }
            if(dp[j] > dp[i])
            {
                dp[i] = dp[j];
                par[i] = -1;
            }
            sn.upd(dp[i], i);
        }
        if(dp[n] != n)
            puts("NO");
        else
        {
            puts("YES");
            string ans;
            int cur = n;
            while(cur != 0)
            {
                if(par[cur] == -1)
                {
                    cur--;
                    ans += "R";
                }
                else
                {
                    int pcur = par[cur];
                    int diff = cur - pcur;
                    ans += "L";
                    for(int j = 0; j < diff - 1; j++)
                        ans += "R";
                    cur = pcur;
                }
            }
            reverse(ans.begin(), ans.end());
            puts(ans.c_str());
        }
    }
}