每日一道算法题——两个不数字的系列之和相加
javascript 实现
跟数列求和差不多
Given two integers a
and b
, which can be positive or negative, find the sum of all the numbers between including them too and return it. If the two numbers are equal return a
or b
.
Note: a
and b
are not ordered!
求两个数的系列相加值
Examples
GetSum(1, 0) == 1 // 1 + 0 = 1
GetSum(1, 2) == 3 // 1 + 2 = 3
GetSum(0, 1) == 1 // 0 + 1 = 1
GetSum(1, 1) == 1 // 1 Since both are same
GetSum(-1, 0) == -1 // -1 + 0 = -1
GetSum(-1, 2) == 2 // -1 + 0 + 1 + 2 = 2
function getSum(a, b) {
//我的思路
//1.range(a,b)
//2.各项相加之和 sum = a+...+b
//3.return sum
}
JavaScript中没有range函数,要自己实现
const getSum = (a, b)=>{
let min = Math.min(a, b)
let max = Math.max(a, b)
return (max-min+1)*(min + max) / 2
}
有规律的排列,用的是排列公式
function getSum(a, b) {
if (a=b) return a
else if (a < b) return a + getSum(a+1, b)
else return a + getSum(a-1, b)
}
function getSum(a, b) {
return (Math.abs(a-b)+1) * (a+b) / 2
}
function getSum(a, b) {
let tmp = 0;
if(a < b) {
while(a <=b ) tmp += a++
} else {
while(a>=b) tmp += a--
}
return tmp
}
js实现sum函数
function sum() {
var x = 0;
for (var i = 0; i < arguments.length; ++i) {
x += arguments[i];
}
return x;
}