链接:
题意:
给出一个长为 的数列,以及 个操作,操作涉及询问区间的最小众数。
思路:
vector维护每个值的出现位置, 预处理第i快到第j块 的众数,然后对不成块的跑暴力,
数组开小了一直wa..找题解,好多题解代码也过不了...
代码:
#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
//#include <memory.h>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <math.h>
#include <stack>
#include <string>
#include <assert.h>
#include <iomanip>
#define MINF 0x3f3f3f3f
using namespace std;
typedef long long LL;
const int MAXN = 1e5+10;
const int MOD = 10007;
int a[MAXN], b[MAXN], Tag[MAXN];
int Num[MAXN];
int Dp[2010][2010];
int Belong[MAXN];
bool Vis[MAXN];
vector<int> Number[MAXN];
int n, part, pos;
inline int read()
{
int ret = 0, c, f = 1;
for(c = getchar(); !(isdigit(c) || c == '-'); c = getchar());
if(c == '-') f = -1, c = getchar();
for(; isdigit(c); c = getchar()) ret = ret * 10 + c - '0';
if(f < 0) ret = -ret;
return ret;
}
void Init(int x)
{
int MaxNum = 0;
int Mode = 0;
memset(Num, 0, sizeof(Num));
for (int i = (x-1)*part+1;i <= n;i++)
{
int p = Belong[i];
Num[a[i]]++;
if (Num[a[i]] > MaxNum)
{
MaxNum = Num[a[i]];
Mode = a[i];
}
if (Num[a[i]] == MaxNum && Mode > a[i])
Mode = a[i];
Dp[x][p] = Mode;
}
}
int GetCnt(int l, int r, int v)
{
// int lp = lower_bound(Number[v].begin(), Number[v].end(), l)-Number[v].begin();
// int rp = upper_bound(Number[v].begin(), Number[v].end(), r)-Number[v].begin();
// return rp-lp+1;
vector<int>::iterator x = upper_bound(Number[v].begin(), Number[v].end(), r);
vector<int>::iterator y = lower_bound(Number[v].begin(), Number[v].end(), l);
return x - y ;
}
int Query(int l, int r)
{
int mode = Dp[Belong[l]+1][Belong[r]-1];
int MaxNum = GetCnt(l, r, mode);
memset(Vis, 0, sizeof(Vis));
Vis[mode] = 1;
for (int i = l;i <= min(Belong[l]*part, r);i++)
{
if (Vis[a[i]])
continue;
Vis[a[i]] = 1;
int cnt = GetCnt(l, r, a[i]);
if (cnt > MaxNum || (MaxNum == cnt && a[i] < mode))
{
MaxNum = cnt;
mode = a[i];
}
}
if (Belong[l] != Belong[r])
{
for (int i = max((Belong[r]-1)*part+1, l);i <= r;i++)
{
if (Vis[a[i]])
continue;
Vis[a[i]] = 1;
int cnt = GetCnt(l, r, a[i]);
if (cnt > MaxNum || (MaxNum == cnt && a[i] < mode))
{
MaxNum = cnt;
mode = a[i];
}
}
}
return mode;
}
int main()
{
// scanf("%d", &n);
n = read();
part = 80;
memset(Tag, -1, sizeof(Tag));
for (int i = 1;i <= n;i++)
{
// scanf("%d", &a[i]);
a[i] = read();
b[i] = a[i];
Belong[i] = (i-1)/part+1;
}
sort(b+1, b+1+n);
pos = unique(b+1, b+1+n)-(b+1);
for (int i = 1;i <= n;i++)
a[i] = lower_bound(b+1, b+1+pos, a[i])-b;
for (int i = 1;i <= Belong[n];i++)
Init(i);
for (int i = 1;i <= n;i++)
Number[a[i]].push_back(i);
int op, l, r, c;
for (int i = 1;i <= n;i++)
{
// scanf("%d%d", &l, &r);
l = read(), r = read();
printf("%d
", b[Query(l, r)]);
}
return 0;
}