134. 加油站

  1. /**
  2.  * @param {number[]} gas
  3.  * @param {number[]} cost
  4.  * @return {number}
  5.  */
  6. var canCompleteCircuit = function(gas, cost) {
  7.   if (gas.length === 1) {
  8.     return gas[0] < cost[0] ? -1 : 0;
  9.   }
  10.   const search = (start) => {
  11.     let i = 0 ;
  12.     let current = 0;
  13.     while (i < gas.length) {
  14.       const next = start + i++;
  15.       current += gas[next % gas.length];
  16.       current -= cost[next % gas.length];
  17.       if (current < 0) {
  18.         return -1;
  19.       }
  20.     }
  21.     return current;
  22.   };
  24.   for (let i = 0; i < gas.length; i ++) {
  25.     if (gas[i] > cost[i]) {
  26.       if (search(i) >= 0) {
  27.         return i;
  28.       }
  29.     }
  30.   }
  31.   return -1;
  32. };

860. 柠檬水找零

  1. /**
  2.  * @param {number[]} bills
  3.  * @return {boolean}
  4.  */
  5. var lemonadeChange = function(bills) {
  6.   let five = 0, ten = 0, twenty = 0;
  7.   for (let i = 0; i < bills.length; i++) {
  8.     if (bills[i] === 5) {
  9.       five += 1;
  10.     } else if (bills[i] === 10) {
  11.       if (five === 0) {
  12.         return false;
  13.       }
  14.       five -= 1;
  15.       ten += 1;
  16.     } else if (bills[i] === 20) {
  17.       if (ten === 0) {
  18.         if (five < 3) {
  19.           return false;
  20.         }
  21.         five -= 3;
  22.       } else if (ten > 0) {
  23.         if (five < 1) {
  24.           return false;
  25.         }
  26.         ten -= 1;
  27.         five -= 1;
  28.         twenty += 1;
  29.       }
  30.     }
  31.   }
  32.   return true;
  33. };

1605. 给定行和列的和求可行矩阵

  1. /**
  2.  * @param {number[]} rowSum
  3.  * @param {number[]} colSum
  4.  * @return {number[][]}
  5.  */
  6. var restoreMatrix = function(rowSum, colSum) {
  7.   const r = rowSum.length;
  8.   const c = colSum.length;
  9.   const m = new Array(r);
  10.   for (let i = 0; i < r; i++) {
  11.     m[i] = new Array(c).fill(0);
  12.     for (let j = 0; j < c; j++) {
  13.       m[i][j] = Math.min(rowSum[i], colSum[j]);
  14.       rowSum[i] -= m[i][j];
  15.       colSum[j] -= m[i][j];
  16.     }
  17.   }
  18.   return m;
  19. };

767. 重构字符串

  1. /**
  2.  * @param {string} s
  3.  * @return {string}
  4.  */
  5. var reorganizeString = function(s) {
  6.   if (s.length === 1) {
  7.     return s;
  8.   }
  9.   let counts = {};
  10.   for (let i = 0; i < s.length; i++) {
  11.     const c = s.charAt(i);
  12.     counts[c] = counts[c] || 0;
  13.     counts[c] += 1;
  14.   }
  16.   counts = Object.entries(counts);
  17.   counts.sort((a, b) => b[1] - a[1]);
  18.   let maxChar = counts.shift();
  19.   let ans = [], maxrow = maxChar[1];
  20.   if (maxrow > (( 1 + s.length) >> 1)) return '';
  22.   for (let i = 0; i < maxrow; i++) {
  23.     ans[i] = [maxChar[0]];
  24.   }
  25.   let row = 0;
  26.   while(counts.length) {
  27.     let [c, max] = counts.shift();
  28.     for (let j = 0; j < max; j++, row++) {
  29.       ans[row % maxrow].push(c);
  30.     }
  31.   }
  32.   // console.log(ans);
  33.   const r = ans.map(item => item.join('')).join('');
  34.   return r;
  35. };