ADACROP.cpp

// Ivan Carvalho
// Solution to https://www.spoj.com/problems/ADACROP/
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 4 * 1e5 + 1;
typedef struct node* pnode;
struct node {
    int val;
    pnode l, r;
    node() : val(0), l(NULL), r(NULL) {}
    void update(int left, int right, int x, int delta) {
        if (left == right) {
            val += delta;
            return;
        }
        val += delta;
        int mid = (left + right) / 2;
        if (x <= mid) {
            if (l == NULL) l = new node;
            l->update(left, mid, x, delta);
        } else {
            if (r == NULL) r = new node;
            r->update(mid + 1, right, x, delta);
        }
    }
    int query(int left, int right, int i, int j) {
        if (left >= i && right <= j) {
            return val;
        }
        int mid = (left + right) / 2;
        if (j <= mid) {
            return (l == NULL) ? 0 : l->query(left, mid, i, j);
        } else if (i >= mid + 1) {
            return (r == NULL) ? 0 : r->query(mid + 1, right, i, j);
        } else {
            return ((l == NULL) ? 0 : l->query(left, mid, i, j)) +
                   ((r == NULL) ? 0 : r->query(mid + 1, right, i, j));
        }
    }
};
map<int, int> conversao;
int vetor[MAXN], n, q, ptr;
pnode raizes[MAXN];
int get_id(int x) {
    if (conversao.count(x)) return conversao[x];
    conversao[x] = ++ptr;
    raizes[ptr] = new node;
    return conversao[x];
}
int main() {
    scanf("%d %d", &n, &q);
    for (int i = 1; i <= n; i++) {
        int x;
        scanf("%d", &x);
        x = get_id(x);
        vetor[i] = x;
        raizes[x]->update(1, n, i, 1);
    }
    for (int vez = 1; vez <= q; vez++) {
        int idx, novo;
        scanf("%d %d", &idx, &novo);
        idx++;
        novo = get_id(novo);
        int velho = vetor[idx];
        raizes[velho]->update(1, n, idx, -1);
        printf("%d\n", raizes[novo]->query(1, n, 1, idx));
        raizes[novo]->update(1, n, idx, 1);
        vetor[idx] = novo;
    }
    return 0;
}