Question

假设我们有一个数组：

array = [1, 0, 0, 0, 1, 0, 1, 1, 1];

我们希望找到一个重复数字的“运行”，其中至少连续三个。在这种情况下，它将是0,0,0和1,1,1的集合。

如何确定哪些索引包含三个或更多的“运行”？

Answer 1

创建

HashMap<Integer, Integer> result = new HashMap<Integer, Integer>();
迭代你的数组存储数组值作为键，并将值的计数作为hashmap中的值：

for (int i: arrayToCount) { Integer count = result.get(i); if (count == null) result.put(i, new Integer(1)); else result.put(i, new Integer(count+1)); }
迭代HashMap并返回您的值。

Answer 2

package algorithms;
import java.util.HashMap;

public class CountOfDupes {
 HashMap<Integer, Integer> myMap = new HashMap<Integer, Integer>();

void incrementDupeCounter(int[] arr){
    int curVal;
    for (int rec : arr){
        if (myMap.containsKey(rec)) {
            curVal = myMap.get(rec);
            myMap.put(rec, curVal + 1);
        } else {
            myMap.put(rec, 1);
        } 
    }
}

void printRunEntries(){
    for (HashMap.Entry<Integer, Integer> entry : myMap.entrySet()) {
        if (entry.getValue() >= 3){
            System.out.println(entry.getKey() + "/" + entry.getValue());
        }
    }
}


public static void main(String[] args) {
    int arr[] = {1, 0, 0, 0, 1, 0, 1, 1, 1};

    CountOfDupes cd = new CountOfDupes();
    cd.incrementDupeCounter(arr);
    cd.printRunEntries();
}

}

Answer 3

运行class以保存运行信息

class Run {
    int first,last,length,value;
    public Run(int value, int first, int last){
        this.value = value;
        this.first = first;
        this.last = last;
        length = last - first + 1;
    }
    public int value(){return value;}
    public int first(){return first;}
    public int last(){return last;}
    public int length(){return length;}
}

示例测试代码

int[] array = new int[]{1, 0, 0, 0, 1, 0, 1, 1, 1};
ArrayList<Run> runs = new ArrayList<Run>();
for(int i=0; i<array.length-2; i++){
    if(array[i+1]==array[i]){
        int j = i + 1;
        int count = 2;
        while(array[j+1] == array[i] && j<array.length - 1){
            count++;
            j++;
        }
        if(count>2){
            runs.add(new Run(array[i], i, j));
        }
        i = j;
    }
}
for(Run r : runs){
    System.out.println("There is a run of " + r.length() + 
            " " + r.value() + "'s from index " + r.first() + 
            " to " + r.last() + ".");
}

如何确定数组中是否有一系列字符？

3 个答案: