javascript_debug/SinglePeak.js at main · willianchu/javascript_debug · GitHub

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// function singlePeak(arr) {
//   let isClimbing = true;
//   let lastValue = arr[0];

//   for (let i = 1; i < arr.length; i++) {
//     if (arr[i] > lastValue) {
//      // is climbing
//      if (isClimbing === false) {
//        return false;
//      }
//      lastValue = arr[i];
//     } else if (arr[i] < lastValue) {
//       // is descending
//       isClimbing = false;
//       lastValue = arr[i];
//     } else {
//       // is a plateau
//       continue;
//     }
//   }
//   return true;
// }


function singlePeak(arr) {
  let isClimbing = true;
  let lastValue = arr[0];
  for (let i = 1; i < arr.length; i++) {
    if (arr[i] > lastValue) {
     // is climbing
     if (isClimbing === false) {
       return false;
     }
     lastValue = arr[i];
    } else if (arr[i] < lastValue) {
      // is descending
      isClimbing = false;
      lastValue = arr[i];
    }
  }
  return true;
}


// let singlePeak = [1,2,3,4,5,6,7,8,9,9,9,8,7,7,6,5,4,3,2,1];
let multiple = [1,2,3,4,5,6,7,8,9,8,9,9,8,7,7,6,5,4,3,2,1];

console.log(singlePeak(singlePeak));