递归与非递归二分查找实现

 

二分查找是针对有序的int数组，查找某数字在该数组的下标。

/**
 * 非递归实现方式
 */
public static void getStrIndex(int[] iA, int i) {
    int minNum = 0;
    int maxNum = iA.length-1;
    int index = 0;
    while(minNum <= maxNum) {
        int mediant = (minNum+maxNum)/2;
        if (i == iA[mediant]) {
            index = mediant;
            break;
        } else if (i < iA[mediant]) {
            maxNum = mediant - 1;
        } else {
            minNum = mediant + 1;
        }
    }
    System.out.println("index="+index); 
}    

 

/**
 * 递归实现方式
 */
public static void recursionGet(int[] iA, int i, int minNum, int maxNum) {
    int index = 0;
    int mediant = (minNum+maxNum)/2;
    if (i == iA[mediant]) {
        index = mediant;
        System.out.println("index="+index); 
    } else if (i < iA[mediant]) {
        recursionGet(iA, i, minNum, mediant - 1);
    } else {
        recursionGet(iA, i, mediant + 1, maxNum);
    }
}