2020 BIT冬训-C++STL J - Hints of sd0061 HDU - 6040
Problem Description
sd0061, the legend of Beihang University ACM-ICPC Team, retired last year leaving a group of noobs. Noobs have no idea how to deal with mm coming contests. sd0061 has left a set of hints for them.
There are nn noobs in the team, the ii-th of which has a rating aiai. sd0061 prepares one hint for each contest. The hint for the j-th contest is a number bj, which means that the noob with the (bj+1)-th
There are nn noobs in the team, the ii-th of which has a rating aiai. sd0061 prepares one hint for each contest. The hint for the j-th contest is a number bj, which means that the noob with the (bj+1)-th
lowest rating is ordained by sd0061 for the j-th contest.
The coach asks constroy to make a list of contestants. constroy looks into these hints and finds out: bi+bj≤bk is satisfied if bi≠bj, bi<bk and bj<bk.
Now, you are in charge of making the list for constroy.
The coach asks constroy to make a list of contestants. constroy looks into these hints and finds out: bi+bj≤bk is satisfied if bi≠bj, bi<bk and bj<bk.
Now, you are in charge of making the list for constroy.
Input
There are multiple test cases (about 10).
For each test case:
The first line contains five integers n,m,A,B,C. (1≤n≤107,1≤m≤100)
The second line contains mm integers, the i-th of which is the number bi of the i-th hint. (0≤bi<n)
The nn noobs' ratings are obtained by calling following function n times, the i-th result of which is ai.
unsigned x = A, y = B, z = C;
unsigned rng61() {
unsigned t;
x ^= x << 16;
x ^= x >> 5;
x ^= x << 1;
t = x;
x = y;
y = z;
z = t ^ x ^ y;
return z;
}
Output
For each test case, output "Case #xx: y1 y2 ⋯⋯ ym" in one line (without quotes), where x indicates the case number starting from 1 and yi (1≤i≤m) denotes the rating of noob for the i-th contest of corresponding case.
Sample Input
3 3 1 1 1 0 1 2 2 2 2 2 2 1 1
Sample Output
Case #1: 1 1 202755 Case #2: 405510 405510
这题真的是烦……对于寻找正确答案。只需要一个nth_element();函数即可。但对于时间优化
由于bi+bj≤bk(bi≠bj, bi<bk and bj<bk)。所以需要先对b进行排序。
然后倒序从最后一个b开始计算(由于上面的式子,所以这样做的收益是巨大的)
但这样对于2.5s的时间限制来说还是不够。所以我们需要注意到上面的一个约束条件
bi≠bj,然后再特判等于情况,另其中一个直接获得答案。即可大幅减少时间。最终入围!!(ಥ_ಥ)
AC代码如下(网上有些代码实测是不能AC的(别问我怎么知道的))
#include<stdio.h> #include<algorithm> using namespace std; const int manx = 1e7+5; unsigned n,m,x,y,z,noobs[manx],id,r; unsigned rng61() { unsigned t; x ^= x << 16; x ^= x >> 5; x ^= x << 1; t = x; x = y; y = z; z = t ^ x ^ y; return z; } pair<unsigned,int> con[105]; int ans[105]; int main(){ while(scanf("%d",&n)!=EOF){ scanf("%d%u%u%u",&m,&x,&y,&z); for(int i=0;i<n;i++) noobs[i]=rng61(); for(int i=0;i<m;i++){ scanf("%u",&con[i].first); con[i].second=i; } sort(con,con+m); con[m].first =n,con[m].second=m; printf("Case #%d:",++id); for(int i=m-1;i>=0;i--){ if(con[i].first==con[i+1].first) ans[con[i].second]=ans[con[i+1].second]; else{ nth_element(noobs,noobs+con[i].first,noobs+con[i+1].first); ans[con[i].second]=noobs[con[i].first]; } } for(int i=0;i<m;i++){ printf(" %u",ans[i]); } printf("\n"); } }

浙公网安备 33010602011771号