[算法设计]hash

hash

基本问题

#include <cstdio>
#define MAXSIZE 1000
void HashInt(int a[], int b[]) {
	bool c[MAXSIZE] = { false };
	int m, n;
	printf("a,b数组元素的个数:");
	scanf("%d%d", &m, &n);
	for (int i = 0; i < m; ++i) {
		int tmp;
		scanf("%d", &tmp);
		a[i] = tmp;
		c[tmp] = true;
	}//空间换取时间
	for (int j = 0; j < n; ++j) {
		int tmp;
		scanf("%d", &tmp);
		b[j] = tmp;
		if (c[tmp]) printf("%d在a中存在",tmp);
	}

}

字符串hash

大写字符hash核心代码:

for(int i=0; i<len(s): ++i){
	id = id*26 + (s[i]- 'A')
}

大小写字母均hash

for(int i=0; i<len(s): ++i){
if(s[i]>'A' && s[i]<'Z')
	id = id*26 + (s[i]- 'A')
else(s[i]>'a' && s[i]<'z')
	id = id*52 + (s[i]-'a') + 26
}