leetcode JS实现

763  partition labels

输入: S = "ababcbacadefegdehijhklij"
输出: [9,7,8]
解释:
划分结果为 "ababcbaca", "defegde", "hijhklij"。
每个字母最多出现在一个片段中。
像 "ababcbacadefegde", "hijhklij" 的划分是错误的，因为划分的片段数较少。 

注意:

1. S的长度在[1, 500]之间。
2. S只包含小写字母'a'到'z'。

function partition_lable (str) {
  function count_times(str) {
    var count_times = []; //统计a-z每个字母出现的位置
    for(var j =0 ; j<26; j++) {count_times.push([]);}
    for(var i=0; i<str.length; i++) {count_times[str[i].charCodeAt()-97].push(i)}
    return count_times
  }
  var count_times = count_times(str); 
  var result = [];
  for(var i=0; i<str.length;) {
   //last代表i对应字母最后一次出现位置
    var last  = Math.max.apply(null, count_times[str[i].charCodeAt()-97]);
    for(var j = i; j<last; j++) {
      if(Math.max.apply(null, count_times[str[j].charCodeAt()-97])>last) {
        last = Math.max.apply(null, count_times[str[j].charCodeAt()-97])
      }
    }
    result.push(last-i+1);
    i= last+1;
  }
  return result
}

762  Prime Number of set Bits in Binary Represention

Given two integers L and R, find the count of numbers in the range [L, R] (inclusive) having a prime number of set bits in their binary representation.

(Recall that the number of set bits an integer has is the number of 1s present when written in binary. For example, 21 written in binary is 10101 which has 3 set bits. Also, 1 is not a prime.)

Example 1:
Input: L = 6, R = 10
Output: 4
Explanation:
6 -> 110 (2 set bits, 2 is prime)
7 -> 111 (3 set bits, 3 is prime)
9 -> 1001 (2 set bits , 2 is prime)
10->1010 (2 set bits , 2 is prime)

Note:

1. L, R will be integers L <= R in the range [1, 10^6].
2. R - L will be at most 10000.

function countPrimeSetBits(L,R) {
  function isPrime(num) {
    if(num<2) return 0;
    if (num === 2) return 1;
    for(var i=2; i<= Math.ceil(num / 2); i++) {if(num%i===0) {return 0}}
    return 1
  }
  var res = 0;
  console.log('L=',typeof L);
  console.log('R=',R);
  for(var j = L; j<=R;j++) {
    res = res + isPrime(j.toString(2).replace(/0/g,'').length);
  }
  return res;
}