CodeForces 732D Exams

思路：二分最早的考试时间，check按最迟考试时间贪心选取。

丑陋的代码,好像快一些？#include <iostream>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <utility>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <cctype>
#define CLEAR(a, b) memset(a, b, sizeof(a))
#define IN() freopen("in.txt", "r", stdin)
#define OUT() freopen("out.txt", "w", stdout)
#define LL long long
#define maxn 100005
#define maxm 1000005
#define mod 1000000007
#define INF 1000000007
#define EPS 1e-6
#define PI 3.1415926535898
#define N 100005
using namespace std;
//-------------------------CHC------------------------------//
int d[maxn], a[maxn], endt[maxn], idx[maxn], t[maxn];
int n, m;

bool cmp(int a, int b) { return endt[a] < endt[b]; }

bool check(int mid) {
CLEAR(endt, 0); CLEAR(t, 0);
for (int i = 1; i <= mid; ++i) endt[d[i]] = i;
for (int i = 1; i <= m; ++i) if (!endt[i]) return false;
for (int i = 1; i <= m; ++i) idx[i] = i;
sort(idx + 1, idx + m + 1, cmp);
int j = 1;
for (int i = 1; i <= m; ++i) {
int cnt = a[idx[i]];
//printf("cnt = %d\n", cnt);
while (j < endt[idx[i]]) {
if (!t[j]) t[j] = 1, cnt--;
if (!cnt) break;
j++;
}
if (cnt) return false;
t[endt[idx[i]]] = 1;
}
return true;
}

int main() {
//IN(); OUT();
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; ++i) scanf("%d", &d[i]);
for (int i = 1; i <= m; ++i) scanf("%d", &a[i]);
int l = 0, r = n + 1;
while (r - l > 1) {
int mid = (l + r) >> 1;
//printf("l = %d, mid = %d, r = %d\n", l, mid, r);
if (check(mid)) r = mid;
else l = mid;
}
if (r > n) printf("-1\n");
else printf("%d\n", r);
return 0;
}改进版

#include <iostream>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <utility>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <cctype>
#define CLEAR(a, b) memset(a, b, sizeof(a))
#define IN() freopen("in.txt", "r", stdin)
#define OUT() freopen("out.txt", "w", stdout)
#define LL long long
#define maxn 100005
#define maxm 1000005
#define mod  1000000007
#define INF 1000000007
#define EPS 1e-6
#define PI 3.1415926535898
#define N 100005
using namespace std;
//-------------------------CHC------------------------------//
int n, m, d[maxn], t[maxn];
struct Node {
int pre, endt;
bool operator<(const Node &r) {
return endt < r.endt;
}
}a[maxn];

bool check(int mid) {
CLEAR(t, 0);
for (int i = 1; i <= m; ++i) a[i].endt = 0;
for (int i = 1; i <= mid; ++i) a[d[i]].endt = i;
sort(a + 1, a + m + 1);
int j = 1;
for (int i = 1; i <= m; ++i) {
if (a[i].endt == 0) return false;
int need = a[i].pre;
while (j < a[i].endt) {
if (!t[j]) --need, t[j] = 1;
if (!need) break;
j++;
}
//printf("need = %d\n", need);
if (need) return false;
t[a[i].endt] = 1;
}
return true;
}

int main() {
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; ++i) scanf("%d", &d[i]);
for (int i = 1; i <= m; ++i) scanf("%d", &a[i].pre);
int mid, l = 0, r = n + 1;
while (r - l > 1) {
mid = (l + r) >> 1;
//printf("l = %d, mid = %d, r = %d\n", l, mid, r);
if (check(mid)) r = mid;
else l = mid;
}
if (r > n) printf("-1\n");
else printf("%d\n", r);
return 0;
}