Function isRangePermutation

src/traces/parcats/calc.js:490–509

* Determine whether an array contains a permutation of the integers from 0 to the array's length - 1 * @param {Array} inds * @return {boolean}

(inds)

 * @return {boolean}
 */
function isRangePermutation(inds) {
    var indsSpecified = new Array(inds.length);

    for(var i = 0; i < inds.length; i++) {
        // Check for out of bounds
        if(inds[i] < 0 || inds[i] >= inds.length) {
            return false;
        }

        // Check for collisions with already specified index
        if(indsSpecified[inds[i]] !== undefined) {
            return false;
        }

        indsSpecified[inds[i]] = true;
    }

    // Nothing out of bounds and no collisions. We have a permutation
    return true;
}