P2564 [SCOI2009]生日礼物 贪心

https://www.luogu.org/problemnew/show/P2564)

题意

有n个珠子，包括k中颜色，找出长度最小的一个区间，使得这个区间中包含所有的颜色。

思路

把n个珠子按照位子排序，然后维护每个珠子最右边能到的位子就行了。

#include <algorithm>
#include <iterator>
#include <iostream>
#include <cstring>
#include <cstdlib>
#include <iomanip>
#include <bitset>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <stack>
#include <cmath>
#include <queue>
#include <list>
#include <map>
#include <set>
#include <cassert>

using namespace std;
#define lson (l, mid, rt << 1)
#define rson (mid + 1, r, rt << 1 | 1)
#define debug(x) cerr << #x << " = " << x << "\n";
#define pb push_back
#define pq priority_queue

typedef long long ll;
typedef unsigned long long ull;
//typedef __int128 bll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef pair<int, pii> p3;

//priority_queue<int> q;//这是一个大根堆q
//priority_queue<int,vector<int>,greater<int> >q;//这是一个小根堆q
#define fi first
#define se second
//#define endl '\n'

#define boost                    \
    ios::sync_with_stdio(false); \
    cin.tie(0)
#define rep(a, b, c) for (int a = (b); a <= (c); ++a)
#define max3(a, b, c) max(max(a, b), c);
#define min3(a, b, c) min(min(a, b), c);

const ll oo = 1ll << 17;
const ll mos = 0x7FFFFFFF;  //2147483647
const ll nmos = 0x80000000; //-2147483648
const int inf = 0x3f3f3f3f;
const ll inff = 0x3f3f3f3f3f3f3f3f; //18
const int mod = 1e9 + 7;
const double esp = 1e-8;
const double PI = acos(-1.0);
const double PHI = 0.61803399; //黄金分割点
const double tPHI = 0.38196601;

template <typename T>
inline T read(T &x) {
    x = 0;
    int f = 0;
    char ch = getchar();
    while (ch < '0' || ch > '9') f |= (ch == '-'), ch = getchar();
    while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
    return x = f ? -x : x;
}

inline void cmax(int &x, int y) {
    if (x < y) x = y;
}
inline void cmax(ll &x, ll y) {
    if (x < y) x = y;
}
inline void cmin(int &x, int y) {
    if (x > y) x = y;
}
inline void cmin(ll &x, ll y) {
    if (x > y) x = y;
}

/*-----------------------showtime----------------------*/

const int maxn = 1e6 + 9;
pll a[maxn];
ll d[100];
int main() {
    int n, k, tot = 0;
    scanf("%d%d", &n, &k);
    for (int i = 1; i <= k; i++) {
        int num;
        scanf("%d", &num);
        for (int j = 1; j <= num; j++) {
            int x;
            scanf("%d", &x);
            a[++tot].fi = x;
            a[tot].se = i;
        }
    }
    sort(a + 1, a + 1 + tot);
    ll ans = 1ll << 31;
    for (int i = 1; i <= tot; i++) {
        d[a[i].se] = a[i].fi;
        ll mx = 0, flag = 1, mn = 1ll << 31;

        for (int j = 1; j <= k; j++) {
            mx = max(mx, d[j]);
            mn = min(mn, d[j]);
            if (d[j] == 0) flag = 0;
        }
        if (flag) ans = min(ans, mx - mn);
    }
    printf("%lld\n", ans);
    return 0;
}