Hi community,

I'm big fan of treaps, but this task makes me feel stupid. https://www.e-olymp.com/en/problems/2957

There is no English translate for some reason. Task: Given N single-element lists with integers 1..10^9, perform next queries: merge L R -> take two already exist lists and create a new one, equal concat(L,R) head L -> create two new lists: first contains first element of L, second — the rest of L. tail L -> create two new lists: first contains all L without last element, second — last element.

For every new list you need to output sum of it's elements.

I've did it with persistent treap — for every merge query: merge(root[L], root[R], root[++versions]), for head — split(root[L], root[nextV()], root[nextV()], 1) for tail — split(root[L], root[nextV()], root[nextV()], cnt[root[L]]-1);

But this fails as for every query it creates at least Log new nodes

struct Treap
{
    int sum[N];
    int nodecnt;
    int L[N] , R[N] , cnt[N];
    int key[N];
    void clear() {
        nodecnt = 0;
    }

code — ~~~~~ typedef long long LL;

define N 13000005

define MOD 1000000007

int root[300005] , c; struct Treap { int sum[N]; int nodecnt; int L[N] , R[N] , cnt[N]; int key[N]; void clear() { nodecnt = 0; } Treap () {clear();} bool hey(int A , int B) { return (LL)rand() * (cnt[A] + cnt[B]) < (LL)cnt[A] * RAND_MAX; } int newnode(int x) { ++ nodecnt , L[nodecnt] = R[nodecnt] = 0; cnt[nodecnt] = 1 , key[nodecnt] = x, sum[nodecnt] = x; return nodecnt; } int copynode(int A) { if (!A) return 0; ++ nodecnt , L[nodecnt] = L[A] , R[nodecnt] = R[A]; cnt[nodecnt] = cnt[A] , key[nodecnt] = key[A], sum[nodecnt] = sum[A]; if (nodecnt == 5000000 — 100) { printf("TREAP\n"); exit(0); } return nodecnt; } void pushup(int x) { cnt[x] = 1; sum[x] = key[x]; if (L[x]) { cnt[x] += cnt[L[x]]; sum[x] = (sum[x] + sum[L[x]]) % MOD; } if (R[x]) { cnt[x] += cnt[R[x]]; sum[x] = (sum[x] + sum[R[x]]) % MOD; } } void merge(int& p , int x , int y) { if (!x || !y) { p = 0; if (x) p = copynode(x); if (y) p = copynode(y); } else if ( hey(x , y) ) { p = copynode(x); merge(R[p] , R[x] , y) , pushup(p); } else { p = copynode(y); merge(L[p] , x , L[y]) , pushup(p); } } void split(int p , int& x , int& y , int size) { if (!size) { x = 0 , y = copynode(p); return; } if (cnt[L[p]] >= size) { y = copynode(p); split(L[p] , x , L[y] , size) , pushup(y); } else { x = copynode(p); split(R[p] , R[x] , y , size — cnt[L[p]] — 1) , pushup(x); } } void print(int p) { if (L[p]) print(L[p]); printf("%d ", key[p]); if (R[p]) print(R[p]); } }; Treap T; char s[10];

int main(void) { int n; scanf("%d", &n); int version = 0; REP(i, n) { int x; scanf("%d", &x); root[++version] = T.newnode(x); }

int q; scanf("%d", &q); REP(i, q) { if (version >= 300005 — 50) { printf("TREAP2\n"); exit(0); } scanf("%s", &s); if (s[0] == 'm') { int x,y; scanf("%d%d", &x, &y); T.merge(root[++version], root[x], root[y]); printf("%d\n", T.sum[root[version]]);

/*(FOR(j, 1, version + 1) {
    printf("%d : ", j);
    T.print(root[j]);
    printf("sum = %d\n", T.sum[root[j]]);
  }*/
}

if (s[0] == 'h') {
  int x;
  scanf("%d", &x);
  int v1 = ++version;
  int v2 = ++version;
  T.split(root[x], root[v1], root[v2], 1);
  printf("%d\n%d\n", T.sum[root[v1]], T.sum[root[v2]]);
}

if (s[0] == 't') {
  int x;
  scanf("%d", &x);
  int v1 = ++version;
  int v2 = ++version;
  T.split(root[x], root[v1], root[v2], T.cnt[root[x]] - 1);
  printf("%d\n%d\n", T.sum[root[v1]], T.sum[root[v2]]);
}

} } ~~~~~

Any ideas how to improve it?