[LeetCode][JavaScript]Unique Paths

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Unique Paths

A robot is located at the top-left corner of a m x n grid (marked ‘Start‘ in the diagram below).

The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked ‘Finish‘ in the diagram below).

How many possible unique paths are there?

Above is a 3 x 7 grid. How many possible unique paths are there?

Note: m and n will be at most 100.

https://leetcode.com/problems/unique-paths/

 

 

 

 

 

地圖中沒有障礙，而且只能往下和往右走。

當前格值就是上方的值加上左邊的值，注意到要從左上往右下算。

 1 /** 2  * @param {number} m 3  * @param {number} n 4  * @return {number} 5  */ 6 var uniquePaths = function(m, n) { 7     var i, j, count = 0, map = []; 8     var len = Math.min(m, n); 9     for(i = 0; i < m; i++){10         map[i] = [];11     }12     for(i = 0; i < len; i++){13         for(j = count; j < n; j++){14             if(count === 0){15                 map[count][j] = 1;16             }else{17                 map[count][j] = map[count - 1][j] + map[count][j - 1];18             }19         }20         for(j = count + 1; j < m; j++){21             if(count === 0){22                 map[j][count] = 1;23             }else{24                 map[j][count] = map[j - 1][count] + map[j][count - 1];25             }26         }27         count++;28     }29     return map[m - 1][n - 1];30 };

 

[LeetCode][JavaScript]Unique Paths