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@ykdojo
Created March 25, 2019 23:42
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/**
* @param {number[]} A
* @return {boolean}
*/
var validMountainArray = function(A) {
if (A.length < 3) {
return false;
}
let i = 0;
let j = 1;
while (A[i] < A[j] && i < A.length) {
i++;
j++;
}
// i should be at the peak
if (i == 0 || j >= A.length) {
return false;
}
while (A[i] > A[j] && j < A.length) {
i++;
j++;
}
if (j < A.length) {
return false;
} else {
return true;
}
};
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