Codeforces Round #545 (Div. 2) D. Camp Schedule //kmp模板

http://codeforces.com/contest/1138/problem/D

重组01串s，使得包含尽量多的子串t

所以要求出字符串的前缀后后缀相同的最大长度。直接kmp

#include<bits/stdc++.h>
using namespace std;
#define mod 100000007
#define LL long long
char s[500005];
char t[500005];
int net[500005];
void GetNext(char* p,int net[])
{
	int pLen = strlen(p);
	net[0] = -1;
	int k = -1;
	int j = 0;
	while (j < pLen)
	{
		if (k == -1 || p[j] == p[k])
		{
			++k;
			++j;
			net[j] = k;
		}
		else
		{
			k = net[k];
		}
	}
}
int main(){
	scanf("%s%s",s,t);
	GetNext(t,net);
	int s0=0,s1=0,t0=0,t1=0;
	int les=strlen(s),let=strlen(t);
	for(int i=0;i<les;i++){
            if(s[i]=='0')s0++;
            else s1++;
	}
	for(int i=0;i<let;i++){
            if(t[i]=='0')t0++;
            else t1++;
	}
	int c=net[let];
	if(s0>=t0&&s1>=t1){
            s0-=t0;
            s1-=t1;
            cout<<t;
	}
	for(int i=0;i<c;i++){
            if(t[i]=='0')t0--;
            else t1--;
	}
	while(s0>=t0&&s1>=t1){
            s0-=t0;
            s1-=t1;
            for(int i=c;i<let;i++){
                cout<<t[i];
            }
	    }
	for(int i=1;i<=s0;i++)
            cout<<0;
        for(int i=1;i<=s1;i++)
            cout<<1;
	return 0;
}

 https://blog.****.net/v_july_v/article/details/7041827#

void GetNext(char* p,int net[])
{
	int pLen = strlen(p);
	net[0] = -1;
	int k = -1;
	int j = 0;
	while (j < pLen) 
	{
		if (k == -1 || p[j] == p[k])
		{
			++k;
			++j;
			net[j] = k;
		}
		else
		{
			k = net[k];
		}
	}
}