【POJ 3368】Frequent values(RMQ)
Description
You are given a sequence of n integers a1 , a2 , ... , an in non-decreasing order. In addition to that, you are given several queries consisting of indices i and j (1 ≤ i ≤ j ≤ n). For each query, determine the most frequent value among the integers ai
Input
The input consists of several test cases. Each test case starts with a line containing two integers n and q (1 ≤ n, q ≤ 100000). The next line contains n integers a1 , ... , an (-100000 ≤ ai ≤ 100000, for each i ∈ {1, ..., n}) separated by spaces. You can assume that for each i ∈ {1, ..., n-1}: ai
query.
The last test case is followed by a line containing a single 0.
Output
For each query, print one line with one integer: The number of occurrences of the most frequent value within the given range.
Sample Input
10 3 -1 -1 1 1 1 1 3 10 10 10 2 3 1 10 5 10 0
Sample Output
1 4 3
題意:
題解:
#include<algorithm> #include<iostream> #include<cstdio> #include<cmath> #include<map> using namespace std; typedef long long ll; const int MAX=100005; int dp[MAX][20]; int mm[MAX]; int f[MAX]; void initrmq(int n,int b[]) { mm[0]=-1; for(int i=1;i<=n;i++) { mm[i]=((i&(i-1))==0)?mm[i-1]+1:mm[i-1]; dp[i][0]=f[i]; } for(int j=1;j<=mm[n];j++) for(int i=1;i+(1<<j)-1<=n;i++) dp[i][j]=max(dp[i][j-1],dp[i+(1<<(j-1))][j-1]); } int rmq(int x,int y) { int k=mm[y-x+1]; return max(dp[x][k],dp[y-(1<<k)+1][k]); } int main() { int n,q,i; while(scanf("%d",&n)&&n) { scanf("%d",&q); int b[MAX]; for(i=1;i<=n;i++) { scanf("%d",&b[i]); if(i==1) { f[i]=1; continue; } if(b[i]==b[i-1]) f[i]=f[i-1]+1; else f[i]=1; } initrmq(n,f); for(i=1;i<=q;i++) { int l,r; scanf("%d%d",&l,&r); int t=l; while(t<=r&&b[t]==b[t-1]) t++; int cnt=rmq(t,r); int ans=max(t-l,cnt); printf("%d\n",ans); } } return 0; }