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leetcode-43. String multiplication

2022-07-03 23:23:00 【Qianfan at the front】

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Code

/** * @param {string} num1 * @param {string} num2 * @return {string} */
//  Analog multiplication 
var multiply = function(num1, num2) {
    
   let len1 = num1.length;
   let len2 = num2.length;
   let res = new Array(len1 + len2).fill(0);

   //  Double traversal analog multiplication 
   for (let i = len1-1; i >= 0; i--) {
    
       for (let j = len2-1; j >= 0; j--) {
    
           //  Analog addition 
           let p1 = i+j;
           let p2 = i+j+1;

           let mul = num1[i] * num2[j];
           let sum = mul + res[p2];
           
           res[p2] = sum%10;
           res[p1] += parseInt(sum/10);
       }
   }

   
   //  The character on the left of the array may be 0
   let i = 0;
   while(res[i] == '0') i++;
   
   //  In the array, except for the front 0 The characters of , Other characters form a string 
   let str = '';
   for (; i<res.length; i++) {
    
       str += res[i];
   }

   //  Leading the array to zero , And form a string 
   // let str = '';
   // let hasZero = true;

   // for (let i = 0; i < res.length; i++) {
    
   // if (res[i] != '0') {
    
   // hasZero = false;
   // }

   // if (!hasZero) {
    
   // str += res[i];
   // }
   // }

   return str.length === 0 ? '0' : str;
};