leetcode tools

A and C.js

const A=(function (){
    const cache={};
    return function(num,base){
        const key=num+'-'+base;
        if(cache[key]){
            return cache[key];
        }
        let ret=1;
        for(var i=0;i<num;i++){
            ret*=base-i;
        }
        cache[key]=ret;
        return ret;
    }
})();
const C=(function (){
    const cache={};
    return function(num,base){
        const key=num+'-'+base;
        if(cache[key]){
            return cache[key];
        }
        let ret=A(num,base);
        for(var i=2;i<=num;i++){
            ret/=i;
        }
        cache[key]=ret;
        return ret;
    }
})();

arr2map.js

const map={};
const farr=[];
nums.forEach(function(v,i){
    if(!map[v]){
        map[v]=0;
        farr.push(v);
    }
    map[v]++;
});