26进制转10进制，找两个有序集合的交集这两个算法均来自网上，自己整理出来仅供学习，研究之用。有兴趣的可以看看

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    任意两个有序集合的交集

import java.util.Arrays; public class Test {     public static void main(String args[]){        int[] b = {4, 6, 7, 7, 7, 7, 8, 8, 9, 10, 100, 130, 130, 140, 150};        int[] a = {2, 3, 4, 4, 4, 4, 7, 8, 8, 8, 8, 9, 100, 130, 150, 160};        int[] c = intersect(a, b);        System.out.println(Arrays.toString(c));    }     public static int[] intersect(int[] a, int[] b) {        if(a[0] > b[b.length - 1] || b[0] > a[a.length - 1]) {            return new int[0];        }        int[] intersection = new int[Math.max(a.length, b.length)];        int offset = 0;        for(int i = 0, s = i; i < a.length && s < b.length; i++) {            while(a[i] > b[s]) {                s++;            }            if(a[i] == b[s]) {                intersection[offset++] = b[s++];            }            while(i < (a.length - 1) && a[i] == a[i + 1]) {                i++;            }        }        if(intersection.length == offset) {            return intersection;        }        int[] duplicate = new int[offset];        System.arraycopy(intersection, 0, duplicate, 0, offset);        return duplicate;    }}

   用a-z表示26进制，26进制与10进制的转换

package com;public class Test {         public static void main(String[] args) {        int n = letter2Number("aaa");        System.out.println(n);    }         public static int letter2Number(String letters) {        if(!letters.matches("[a-zA-Z]+")) {            throw new IllegalArgumentException("Format ERROR!");        }        char[] chs = letters.toLowerCase().toCharArray();         int result = 0;        for(int i = chs.length - 1, p = 1; i >= 0; i--) {                        result += getNum(chs[i]) * p;            p *= 26;        }        return result;    }         private static int getNum(char c) {        return c - 'a' + 1;    }

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