Leetcode 735 行星碰撞

 

　　C:

void dealLeft(int *asteroids, int size, int point)
{
    if (point >= size)
        return;
    if (asteroids[point] >= 0)
        return;
    int left = point - 1;
    while (left >= 0 && asteroids[left] == 0)
        left--;
    if (left == -1 || asteroids[left] < 0)
        return;
    if (asteroids[point] + asteroids[left] > 0)
        asteroids[point] = 0;
    else if (asteroids[point] + asteroids[left] < 0)
    {
        asteroids[left] = 0;
        dealLeft(asteroids, size, point);
    }
    else
        asteroids[left] = asteroids[point] = 0;
}

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int *asteroidCollision(int *asteroids, int asteroidsSize, int *returnSize)
{
    for (int i = 0; i < asteroidsSize; i++)
    {
        dealLeft(asteroids, asteroidsSize, i);
    }
    int size = 0;
    for (int i = 0; i < asteroidsSize; i++)
        if (asteroids[i] != 0)
            size++;
    *returnSize = size;
    if (size > 0)
    {
        int *reArr = (int *)malloc(sizeof(int) * size);
        int point = 0;
        for (int i = 0; i < asteroidsSize; i++)
            if (asteroids[i] != 0)
            {
                reArr[point] = asteroids[i];
                point++;
            }
        return reArr;
    }
    else
        return NULL;
}

　　JAVA:

public final int[] asteroidCollision(int[] asteroids) {
        for (int i = 0; i < asteroids.length; i++) {
            searchLeft(asteroids, i);
        }
        int len = 0, point = 0;
        for (int i = 0; i < asteroids.length; i++)
            if (asteroids[i] != 0) len++;
        int[] reArr = new int[len];
        for (int i = 0; i < asteroids.length; i++) {
            if (asteroids[i] != 0) {
                reArr[point] = asteroids[i];
                point++;
            }
        }
        return reArr;
    }

    private final void searchLeft(int[] asteroids, int point) {
        if (asteroids[point] > 0) return;
        int left = point - 1;
        while (left >= 0 && asteroids[left] == 0) left--;
        if (left == -1 || asteroids[left] < 0) return;
        if (asteroids[left] + asteroids[point] > 0) asteroids[point] = 0;
        else if (asteroids[left] + asteroids[point] < 0) {
            asteroids[left] = 0;
            searchLeft(asteroids, point);
        } else {
            asteroids[point] = 0;
            asteroids[left] = 0;
        }
    }

　　JS:

/**
 * @param {number[]} asteroids
 * @return {number[]}
 */
var asteroidCollision = function (asteroids) {
    for (let i = 0; i < asteroids.length; i++) dealLeft(asteroids, i);
    let reArr = [];
    for (let i = 0; i < asteroids.length; i++)
        if (asteroids[i]) reArr.push(asteroids[i]);
    return reArr;
};

//处理左边反向的
var dealLeft = function (asteroids, point) {
    if (asteroids[point] > 0) return;
    let left = point - 1;
    while (left >= 0 && asteroids[left] == 0) left--;
    if (left == -1 || asteroids[left] < 0) return;
    if (asteroids[left] + asteroids[point] > 0) asteroids[point] = 0;
    else if (asteroids[left] + asteroids[point] < 0) {
        asteroids[left] = 0;
        dealLeft(asteroids, point);
    } else {
        asteroids[left] = 0;
        asteroids[point] = 0;
    }
}