题解 | #字符个数统计#
字符个数统计
https://www.nowcoder.com/practice/eb94f6a5b2ba49c6ac72d40b5ce95f50
const rl = require("readline").createInterface({ input: process.stdin });
rl.on('line', function(line){
let arr = Array.from(new Set(line.split('')))
console.log(arr.length)
})
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