My JS algorithm climb pit tour – gas station

Day 42: Li Kou question 134, gas station

Address: leetcode-cn.com/problems/ga…

If the sum is less than zero, oil will not be enough. If the sum is greater than zero, oil will be enough. So you add them, you go over them, and you find a place where you don’t end with zero.

var canCompleteCircuit = function(gas, cost) {
  let res = [];
  let flag = -1;
  let sum = 0;
  let ser = 0;
  for(let i = 0; i < gas.length; i++)
  {
    res[i] = gas[i] - cost[i];
  }
  if(res.reduce((prev, next, index, array) => prev + next) < 0)
  {
    return -1;
  }
  for(let i = 0; i < res.length; i++)
  {
    if(flag === -1 && res[i] > 0)
    {
      sum = res[i];
      ser = i;
      flag = 0;
    }
    else if(flag === 0)
    {
      sum += res[i];
    }
    if(sum < 0)
    {
      flag = -1;
    }
  }
  return ser;
};
Copy the code

If you’re operating on an array, it’s going to consume less memory, so I’ll give cost a null.

Ha ha ha ha ha, smart as me.