【HDOJ】3601 Coach Yehr’s punishment

RMQ+dp+二分。
最好还是离散化一下再处理，通过dp求得每个位置的上一次出现的位置pre数组，从而求得不重复的长度len。
然后RMQ可以预处理区间的最大值，pre是个单调非递减数列。每次查询时，二分可以找到超过l的位置。
注意这个位置k可能超过r。因此最大值为max(k-l, RMQ(k, r) && k<=r)。

/* 3603 */
#include <iostream>
#include <sstream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1

const int maxn = 1e6+5;
int pre[maxn], len[maxn], pos[maxn];
int dp[20][maxn];
int a[maxn];
int n;

void init_RMQ(int n) {
    int i, j;
    
    for (i=1; i<=n; ++i)
        dp[0][i] = len[i];
    for (j=1; (1<<j)<=n; ++j)
        for (i=1; i+(1<<j)-1<=n; ++i)
            dp[j][i] = max(dp[j-1][i], dp[j-1][i+(1<<(j-1))]);
}

int RMQ(int l, int r) {
    if (l > r)
        swap(l, r);
    
    int k = 0;
    
    while (1<<(k+1) <= r-l+1)
        ++k;
    
    return max(dp[k][l], dp[k][r-(1<<k)+1]);
}

void solve() {
    memset(pos, 0, sizeof(pos));
    rep(i, 1, n+1) {
        if (pos[a[i]] == 0)
            pre[i] = 0;
        else
            pre[i] = pos[a[i]];
        pre[i] = max(pre[i], pre[i-1]);
        pos[a[i]] = i;
        len[i] = i - pre[i];
    }
    
    init_RMQ(n);
    
    int q;
    int l, r;
    int ans;
    
    scanf("%d", &q);
    while (q--) {
        scanf("%d %d", &l, &r);
        if (l > r)
            swap(l, r);
        int k = lower_bound(pre+l, pre+r+1, l) - pre;
        ans = k - l;
        if (k <= r)
            ans = max(ans, RMQ(k, r));
        printf("%d
", ans);
    }
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    while (scanf("%d", &n)!=EOF) {
        rep(i, 1, n+1)
            scanf("%d", &a[i]);
        solve();
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}

数据生成器。

from random import randint, shuffle
import shutil
import string


def GenDataIn():
    with open("data.in", "w") as fout:
        t = 1
        bound = 10**3
        for tt in xrange(t):
            n = randint(100, 200)
            fout.write("%d
" % (n))
            dataList = []
            for i in xrange(n):
                x = randint(1, 100)
                dataList.append(x)
            fout.write(" ".join(map(str, dataList)) + "
")
            q = randint(100, 200)
            fout.write("%d
" % (q))
            for i in xrange(q):
                l = randint(1, n)
                r = randint(l, n)
                fout.write("%d %d
" % (l, r))
                
def MovDataIn():
    desFileName = "F:eclipse_prjworkspacehdojdata.in"
    shutil.copyfile("data.in", desFileName)

    
if __name__ == "__main__":
    GenDataIn()
    MovDataIn()