hihocoder-1327-分割字符串--贪心

#include <cstdio> 
#include <cstring> 

const int MAXN = 100000 + 10; 

bool Check(const int a[], const int len, const int b){
	for(int i=0; i<len; ++i){
		if(a[i] > (b+1)/2){
			return false; 
		}
	}
	return true; 
}

int main(){
	freopen("in.txt", "r", stdin); 

	int len; 
	char ch[MAXN], ans[MAXN]; 
	int cnt[26]; 

	while(scanf("%s", ch) != EOF){
		getchar(); 
		len = strlen(ch);
		memset(cnt, 0, sizeof(cnt));  
		for(int i=0; i<len; ++i){
			++cnt[ ch[i] - ‘a‘ ]; 
		}
		bool ans_flag = true; 

		for(int i=0; i<len; ++i){
			bool ok = false; 

			for(int j=0; j<26; ++j){ 
				if(cnt[j] > 0 && (i==0 || ans[i-1] != j + ‘a‘ ) ){ 
					--cnt[j]; 
					bool vali = Check(cnt, 26, len-i-1); 
					ok = ok || vali;  
					if(vali){ 
						ans[i] = ‘a‘ + j; 
						break; 
					}else{
						++cnt[j]; 
					}
				}
			} 
			if(!ok) {
				ans_flag = false; 
				break; 
			}
		}
		ans[len] = ‘\0‘; 
		if(ans_flag){
			printf("%s\n", ans );
		}else{
			printf("INVALID\n");
		}
	}
	return 0; 
}