264

class Solution {
    public int nthUglyNumber(int n) {
        int[] dp = new int[n];
        dp[0] = 1;
        int i2 = 0, i3 = 0, i5 = 0;
        for(int i = 1; i < n; i++){
            int min = Math.min(dp[i2]*2, Math.min(dp[i3]*3, dp[i5]*5));//比较三数的方法
            if(min == dp[i2]*2)i2++;
            if(min == dp[i3]*3)i3++;
            if(min == dp[i5]*5)i5++;
            dp[i] = min;
        }
        return dp[n-1];
    }
}