UV and UV 35

UV and UV 35

Link to the question: Ultraviolet A 11235-Frequent values

Given a non-descending integer array, it is required to calculate some queries (I, j), answer ai, ai + 1 ,..., The maximum number of occurrences in aj.

Solution: Because the sequence is non-descending, the same numbers must be tied together, so we use the o (n) method to process the intervals of the same numbers in each segment. Then, for each query:

• Num [I] = num [j]: j −i + 1
• Numi =numj: max (RMQ (righti + 1, reftj −1), max (righti −i + 1, j −leftj + 1 ))

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int maxn = 1e5+5;int N, Q, num[maxn], rmq[maxn][20];int left[maxn], right[maxn];void RMQ_init () {    memset(rmq, 0, sizeof(rmq));    for (int i = 1; i <= N; i++)        rmq[i][0] = right[i] - left[i] + 1;    for (int j = 1; (1<<j) <= N; j++) {        for (int i = 1; i + (1<<j) - 1 <= N; i++)            rmq[i][j] = max(rmq[i][j-1], rmq[i+(1<<(j-1))][j-1]);    }}void init () {    for (int i = 1; i <= N; i++)        scanf("%d", &num[i]);    left[1] = 1;    for (int i = 2; i <= N; i++) {        if (num[i] == num[i-1])            left[i] = left[i-1];        else            left[i] = i;    }    right[N] = N;    for (int i = N-1; i >= 1; i--) {        if (num[i] == num[i+1])            right[i] = right[i+1];        else            right[i] = i;    }    RMQ_init();}int RMQ (int L, int R) {    if (L > R)        return 0;    int k = 0;    while (1<<(k+1) <= R-L+1)        k++;    return max(rmq[L][k], rmq[R-(1<<k)+1][k]);}int main () {    while (scanf("%d%d", &N, &Q) == 2 && N) {        init();        int x, y;        for (int i = 0; i < Q; i++) {            scanf("%d%d", &x, &y);            if (num[x] == num[y])                printf("%d\n", y - x + 1);            else                printf("%d\n", max(RMQ(right[x]+1, left[y]-1), max(right[x] - x + 1, y - left[y] + 1)));        }    }    return 0;}