function solve( s , t ) { let sum = ""; let i = s.length - 1, j = t.length - 1; let carry = 0; while(i >= 0 || j >= 0){ //这里采用的是取反运算符,当s或者t角标越界时,结果是undefined,~~undefined = 0 // +undefined = NaN, parseInt(undefined) = NaN let temp = ~~s[i] + ~~t[j] + carry; if(temp &...