HDU 5583 Kingdom of Black and White [Ad Hoc]

2015上海区域赛 K题

Description

给一串0和1，然后你可以变一个
这样就分成了若干块
求然后每块长度的平方和最大

Algorithm

两种情况
1.长度大于1
这样变两头

2.长度=1，这样3段就练成一段

Hint

貌似必须用vector，不然超时？

Code

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <cmath>#include <vector>using namespace std;string s;void solve(){  vector<long long> a;  cin>>s;  a.push_back(0);  a.push_back(1);  long long ans0 = 0;  for (int i = 1; i < s.size(); i++)    if (s[i] == s[i - 1])      a[a.size() - 1]++;    else    {      a.push_back(1);    }  a.push_back(0);  for (int i = 0; i < a.size(); i++)    ans0 += (a[i] * a[i]);  long long ans = ans0;  for (int i = 1; i < a.size() - 1; i++)  if (a[i] > 1)  {    long long t = ans0 + (a[i] - 1) * (a[i] - 1) + (a[i + 1] + 1) * (a[i + 1] + 1) - a[i] * a[i] - a[i + 1] * a[i + 1];    if (t > ans) ans = t;              t = ans0 + (a[i] - 1) * (a[i] - 1) + (a[i - 1] + 1) * (a[i - 1] + 1) - a[i] * a[i] - a[i - 1] * a[i - 1];    if (t > ans) ans = t;  }else    {      long long t = ans0 + (a[i - 1] + 1 + a[i + 1]) * (a[i - 1] + 1 + a[i + 1]) - (a[i - 1] * a[i - 1] + a[i] * a[i] + a[i + 1] * a[i + 1]);      if (t > ans) ans = t;    }  cout << ans << endl;}int main(){//  freopen("input.txt", "r", stdin);  int n;  scanf("%d\n", &n);  for (int i = 1; i <= n; i++)  {    printf("Case #%d: ", i);    solve();  }}