*[hackerrank]ACM ICPC Team
https://www.hackerrank.com/contests/w6/challenges/acm-icpc-team
这道题在contest的时候数据量改小过,原来的数据量需要进行优化才能过。参考了:http://chasethered.com/2014/07/hackerrank-weekly-challenge-6-problem-1/
首先是转化成int32的数组,然后N^N的复杂度两两比较求bit数。求bit中1的个数有几种做法:
- x & (x - 1)
- Hamming weight的经典求法,基于树状累加:http://en.wikipedia.org/wiki/Hamming_weight
- 内存足够大可以查表得;
#include <iostream> #include <vector> #include <string> using namespace std; int bitCount(unsigned int u) { unsigned int uCount; uCount = u - ((u >> 1) & 033333333333) - ((u >> 2) & 011111111111); return ((uCount + (uCount >> 3)) & 030707070707) % 63; } int main() { int N; int M; cin >> N >> M; vector<vector<int>> bm(N); int len = (M - 1) % 32 + 1; for (int i = 0; i < N; i++) { bm[i].resize(len); } for (int i = 0; i < N; i++) { string s; cin >> s; int k = -1; for (int j = 0; j < M; j++) { if (j % 32 == 0) k++; bm[i][k] *= 2; bm[i][k] += (int) (s[j] - '0'); } } int topicCount = 0; int teamCount = 0; for (int i = 0; i < N; i++) { for (int j = i + 1; j < N; j++) { int local = 0; for (int k = 0; k < len; k++) { unsigned int tmp = bm[i][k] | bm[j][k]; int count = bitCount(tmp); local += count; } if (local > topicCount) { topicCount = local; teamCount = 1; } else if (local == topicCount) { teamCount++; } } } cout << topicCount << endl; cout << teamCount << endl; return 0; }