Optimize all combinations that meet the conditions from top to bottom
That is DP
EX
index year month
0 0 1
1 0 3
2 1 2
3 1 11
4 1 12
5 2 5
6 2 8
7 3 4
dp[0]=1
dp[1]=dp[0]+1
dp[2]=dp[1]+1 (dp[0]+1) <-- does not meet the condition
dp[3]=dp[2]+1 (dp[1]+1 dp[0]+1)<-- does not meet the condition
…
dp[i]=min(dp[i],dp[j]+1) j from i-1 to 0
That is, DP gives the minimum and satisfying pairing from above to below, but the + sign must be retained, so as soon as the + sign is encountered, immediately break
So all permutations and combinations after the + sign must have a + sign
//
// GGGGGGGGGGGGG CCCCCCCCCCCCC AAA
// GGG::::::::::::G CCC::::::::::::C A:::A
// GG:::::::::::::::G CC:::::::::::::::C A:::::A
// G:::::GGGGGGGG::::G C:::::CCCCCCCC::::C A:::::::A
// G:::::G GGGGGG C:::::C CCCCCC A:::::::::A
//G:::::G C:::::C A:::::A:::::A
//G:::::G C:::::C A:::::A A:::::A
//G:::::G GGGGGGGGGGC:::::C A:::::A A:::::A
//G:::::G G::::::::GC:::::C A:::::A A:::::A
//G:::::G GGGGG::::GC:::::C A:::::AAAAAAAAA:::::A
//G:::::G G::::GC:::::C A:::::::::::::::::::::A
// G:::::G G::::G C:::::C CCCCCC A:::::AAAAAAAAAAAAA:::::A
// G:::::GGGGGGGG::::G C:::::CCCCCCCC::::C A:::::A A:::::A
// GG:::::::::::::::G CC:::::::::::::::C A:::::A A:::::A
// GGG::::::GGG:::G CCC::::::::::::C A:::::A A:::::A
// GGGGGG GGGG CCCCCCCCCCCCCAAAAAAA AAAAAAA
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <climits>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <cctype>
#include <utility>
#include <ctime>
using namespace std;
#ifdef DEBUG
#define debug(...) printf("DEBUG: "),printf(\_\_VA\_ARGS\_\_)
#define gettime() end\_time=clock();printf("now running time is %.7f\\n",(float)(end\_time - start\_time)/CLOCKS\_PER\_SEC);
#else
#define debug(...)
#define gettime()
#endif
typedef unsigned int uint;
typedef long long int Int;
#define Set(a,s) memset(a,s,sizeof(a))
#define Write(w) freopen(w,"w",stdout)
#define Read(r) freopen(r,"r",stdin)
#define Pln() printf("\\n")
#define I\_de(x,n)for(int i=0;i<n;i++)printf("%d ",x\[i\]);Pln()
#define De(x)printf(#x"%d\\n",x)
#define For(i,x)for(int i=0;i<x;i++)
#define CON(x,y) x##y
#define Pmz(dp,nx,ny)for(int hty=0;hty<ny;hty++){for(int htx=0;htx<nx;htx++){\\
printf("%d ",dp\[htx\]\[hty\]);}Pln();}
#define M 1055
#define PII pair<int,int\>
#define PB push\_back
#define oo INT\_MAX
#define Set\_oo 0x3f
#define FOR(it,c) for(\_\_typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define eps 1e-6
clock\_t start\_time=clock(), end\_time;
bool xdy(double x,double y){return x>y+eps;}
bool xddy(double x,double y){return x>y-eps;}
bool xcy(double x,double y){return x<y-eps;}
bool xcdy(double x,double y){return x<y+eps;}
int min3(int x,int y,int z){
int tmp=min(x,y);
return min(tmp,z);
}
int max3(int x,int y,int z){
int tmp=max(x,y);
return max(tmp,z);
}
struct logss{
int time;
bool keep;
int year;
}logs\[M\];
int n;
char cl\[20\];
int start,ed;
int cur;
int dp\[1024\];
void solve(){
// for(int i=0;i<start;i++)dp\[i\]=1;
dp\[start\]=1;
for(int i=start+1;i<n;i++){
dp\[i\]=dp\[i-1\]+1;
for(int j=i-1;j>=0;j--){
if(logs\[i\].year==logs\[j\].year){
dp\[i\]=min(dp\[i\],dp\[j\]+1);
}else if(logs\[i\].year==logs\[j\].year+1&&logs\[i\].time<logs\[j\].time){
dp\[i\]=min(dp\[i\],dp\[j\]+1);
}else break;
if(logs\[j\].keep)break;
}
}
int res=dp\[n-1\];
for(int i=n-2;i>=ed&&logs\[i\].year==cur;i--){
// printf("%d\\n",dp\[i\]);
res=min(res,dp\[i\]);
}
printf("%d\\n",res);
}
int main() {
ios\_base::sync\_with\_stdio(0);
while(~scanf("%d",&n)&&n){
for(int i=0;i<n;i++){
int w,x,y,z,num;
char c;
scanf("%d:%d:%d:%d %s %c",&w,&x,&y,&z,cl,&c);
logs\[i\].time=((w\*31+x)\*24+y)\*60+z;
if(c=='+')logs\[i\].keep=true;
else logs\[i\].keep=false;
}
logs\[0\].year=0;
start=(logs\[0\].keep)?0:-1;
ed=cur=0;
for(int i=1;i<n;i++){
if(start==-1&&logs\[i\].keep)start=i;
if(logs\[i\].keep)ed=i;
if(logs\[i-1\].time<=logs\[i\].time){
logs\[i\].year=logs\[i-1\].year;
}else{
logs\[i\].year=logs\[i-1\].year+1;
cur++;
}
}
solve();
}
}