@Yano 2019-01-13T16:50:37.000000Z 字数 1046 阅读 1488

# LeetCode 949 Largest Time for Given Digits

LeetCode

# 题目描述

Given an array of 4 digits, return the largest 24 hour time that can be made.

The smallest 24 hour time is 00:00, and the largest is 23:59. Starting from 00:00, a time is larger if more time has elapsed since midnight.

Return the answer as a string of length 5. If no valid time can be made, return an empty string.

Example 1:

Input: [1,2,3,4]
Output: "23:41"


Example 2:

Input: [5,5,5,5]
Output: ""


Note:

A.length == 4
0 <= A[i] <= 9


# 代码

public String largestTimeFromDigits(int[] A) {    int[] ans = new int[]{-1};    timeDfs(A, ans, 0, 0, new boolean[A.length]);    if (ans[0] == -1) {        return "";    }    return getRes(ans[0]);}private String getRes(int time) {    int hour = time / 100;    int minute = time % 100;    return (hour < 10 ? "0" + hour : hour) + ":" + (minute < 10 ? "0" + minute : minute);}private void timeDfs(int[] A, int[] ans, int num, int count, boolean[] used) {    if (count == A.length) {        ans[0] = Math.max(ans[0], num);        return;    }    for (int i = 0; i < A.length; i++) {        if (!used[i]) {            int cal = num * 10 + A[i];            if (count == 1 && (cal < 0 || cal >= 24)) {                continue;            }            if (count == 3 && (cal % 100 < 0 || cal % 100 >= 60)) {                continue;            }            used[i] = true;            timeDfs(A, ans, cal, count + 1, used);            used[i] = false;        }    }}

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