dp[i][0] += dp[i - 1][0]边界初始值
dp[0][j] += dp[0][j - 1]边界初始值
dp[i][j] += Math.min(dp[i - 1][j], dp[i][j - 1]) 非边界初始值
var minPathSum = function (dp) {
var m = dp.length, n = dp[0].length
for (var i = 1; i < m; i++) {
dp[i][0] += dp[i - 1][0]
}
for (var j = 1; j < n; j++) {
dp[0][j] += dp[0][j - 1]
}
for (var i = 1; i < m; i++) {
for (var j = 1; j < n; j++) {
dp[i][j] += Math.min(dp[i - 1][j], dp[i][j - 1])
}
}
return dp[m - 1][n - 1]
};