POJ2159 Ancient Cipher

2159:Ancient Cipher

題目分析：很簡單的一道題。大意是判斷兩個字符序列是否可以通過字符替換（substitution ）和交換（permutation）變成對方。初看似乎需要窮舉所有substitution和permutation序列，但細想後發現：

1.permutation讓序列不用考慮順序問題，可以看作是兩個字符集合，題目簡化爲判斷兩個字符集合是否可通過substitution得到。

2.substitution是任意的，只要兩個序列中兩個字符出現的次數相同，就可以替換。如果整個集合A中的字符都能在集合B中找到出現次數相同的字符，則A和B可以通過substitution得到。更進一步，只要統計集合A和集合B中出現次數爲p(p>=1)的不同字符數目是否相等即可。

代碼：

#include <stdio.h>
#include <string.h>
int main(){
	char encryted[105];
	char original[105];
	int mapEN[26],mapOR[26];
	memset(mapEN,0,sizeof(mapEN));
	memset(mapOR,0,sizeof(mapOR));

	scanf("%s%s",encryted,original);
	for(int i=0; encryted[i] != '\0'; i++){
		mapEN[encryted[i]-'A']++;
		mapOR[original[i]-'A']++;
	}

	int charCount[105];
	memset(charCount,0,sizeof(charCount));
	for(int i = 0; i<26; i++){
		charCount[mapEN[i]]++;
		charCount[mapOR[i]]--;
	}

	bool flag = true;
	for(int i = 0; i < 105; i++){
		if(charCount[i] != 0){
			flag = false;
			break;
		}
	}

	if(flag == true)
		printf("YES\n");
	else
		printf("NO\n");
	return 0;
}

題目：

時間限制: 1000ms 內存限制: 65536kB
描述
Ancient Roman empire had a strong government system with various departments, including a secret service department. Important documents were sent between provinces and the capital in encrypted form to prevent eavesdropping. The most popular ciphers in those times were so called substitution cipher and permutation cipher.
Substitution cipher changes all occurrences of each letter to some other letter. Substitutes for all letters must be different. For some letters substitute letter may coincide with the original letter. For example, applying substitution cipher that changes all letters from 'A' to 'Y' to the next ones in the alphabet, and changes 'Z' to 'A', to the message "VICTORIOUS" one gets the message "WJDUPSJPVT".
Permutation cipher applies some permutation to the letters of the message. For example, applying the permutation <2, 1, 5, 4, 3, 7, 6, 10, 9, 8> to the message "VICTORIOUS" one gets the message "IVOTCIRSUO".
It was quickly noticed that being applied separately, both substitution cipher and permutation cipher were rather weak. But when being combined, they were strong enough for those times. Thus, the most important messages were first encrypted using substitution cipher, and then the result was encrypted using permutation cipher. Encrypting the message "VICTORIOUS" with the combination of the ciphers described above one gets the message "JWPUDJSTVP".
Archeologists have recently found the message engraved on a stone plate. At the first glance it seemed completely meaningless, so it was suggested that the message was encrypted with some substitution and permutation ciphers. They have conjectured the possible text of the original message that was encrypted, and now they want to check their conjecture. They need a computer program to do it, so you have to write one.
輸入
Input contains two lines. The first line contains the message engraved on the plate. Before encrypting, all spaces and punctuation marks were removed, so the encrypted message contains only capital letters of the English alphabet. The second line contains the original message that is conjectured to be encrypted in the message on the first line. It also contains only capital letters of the English alphabet.
The lengths of both lines of the input are equal and do not exceed 100.
輸出
Output "YES" if the message on the first line of the input file could be the result of encrypting the message on the second line, or "NO" in the other case.
樣例輸入
JWPUDJSTVP
VICTORIOUS
樣例輸出
YES